refactor(lang): rename the str type (and stringify builtin) to string

Expand the abbreviated string type and its conversion builtin to the full
word everywhere:
  str            ->  string        (the immutable-string type)
  str(x) -> str  ->  string(x) -> string   (the stringify builtin;
                                            what `{…}` interpolation calls)

Types are recognized by identifier, and llty maps both spellings to LLVM
`ptr`, so this is an atomic source rewrite: type annotations, the Ludic
type tags, the builtin name/dispatch, and the interpolation desugar, plus
the grammars, LSP, docs (type-str -> type-string, fn-str -> fn-string), and
inventory. int/bool stay (universally accepted, like Math).

Reseeded; C-free fixpoint holds; all suites green (45/24/29); site + check.py OK.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

docs/language/text/_section.md

@@ -4,4 +4,4 @@ title: Text
 order: 6
 ---
 
-String queries and building over <code>str</code> values — length, character access, substrings, search, prefix/suffix tests, and int conversion. Arguments are positional. Strings are byte sequences, so indices and lengths count bytes.
+String queries and building over <code>string</code> values — length, character access, substrings, search, prefix/suffix tests, and int conversion. Arguments are positional. Strings are byte sequences, so indices and lengths count bytes.

docs/language/text/text-char_at.md

@@ -19,7 +19,7 @@ Parameters:
 
 ```ludic
 program FirstIsDigit {
-  var entry: str = "7up"
+  var entry: string = "7up"
 
   handler Check phase Update {
     let c = Text.char_at(entry, 0)

docs/language/text/text-concat.md

@@ -4,7 +4,7 @@ name: Text.concat
 category: text
 kind: namespace-method
 tokens: Text.concat
-sig: Text.concat(a, b) -> str
+sig: Text.concat(a, b) -> string
 tip: Join two strings into a new one.
 order: 8
 ns: Text
@@ -19,7 +19,7 @@ Parameters:
 
 ```ludic
 program Greeting {
-  var name: str = "world"
+  var name: string = "world"
 
   handler Build phase Update {
     let line = Text.concat("hello ", name)   # "hello world"

docs/language/text/text-contains.md

@@ -19,7 +19,7 @@ Parameters:
 
 ```ludic
 program Filter {
-  var line: str = "error: disk full"
+  var line: string = "error: disk full"
 
   handler Scan phase Update {
     if Text.contains(line, "error") {

docs/language/text/text-ends_with.md

@@ -19,7 +19,7 @@ Parameters:
 
 ```ludic
 program IsImage {
-  var filename: str = "hero.png"
+  var filename: string = "hero.png"
 
   handler Classify phase Update {
     let png = Text.ends_with(filename, ".png")   # true

docs/language/text/text-equals.md

@@ -19,8 +19,8 @@ Parameters:
 
 ```ludic
 program Guess {
-  var answer: str = "swordfish"
-  var attempt: str = "swordfish"
+  var answer: string = "swordfish"
+  var attempt: string = "swordfish"
 
   handler Check phase Update {
     if Text.equals(attempt, answer) {

docs/language/text/text-from_int.md

@@ -4,14 +4,14 @@ name: Text.from_int
 category: text
 kind: namespace-method
 tokens: Text.from_int
-sig: Text.from_int(n) -> str
+sig: Text.from_int(n) -> string
 tip: Render an integer as a string.
 order: 10
 ns: Text
 member: from_int
 ---
 
-Returns the decimal text of the integer <code>n</code> — <code>Text.from_int(1234)</code> is <code>"1234"</code>, and negatives keep their sign. It is the same conversion as the bare <code>str(n)</code> and the inverse of <code>Text.to_int</code>. Use it when you need a number as characters — to measure its width, concatenate it, or store it — though drawing a number to the screen is better done with <code>Screen.draw_number</code>.
+Returns the decimal text of the integer <code>n</code> — <code>Text.from_int(1234)</code> is <code>"1234"</code>, and negatives keep their sign. It is the same conversion as the bare <code>string(n)</code> and the inverse of <code>Text.to_int</code>. Use it when you need a number as characters — to measure its width, concatenate it, or store it — though drawing a number to the screen is better done with <code>Screen.draw_number</code>.
 
 Parameters:
 - `n` — the integer to render

docs/language/text/text-index_of.md

@@ -19,7 +19,7 @@ Parameters:
 
 ```ludic
 program KeyValue {
-  var pair: str = "hp=42"
+  var pair: string = "hp=42"
 
   handler Parse phase Update {
     let eq = Text.index_of(pair, "=")            # 2

docs/language/text/text-join.md

@@ -4,7 +4,7 @@ name: Text.join
 category: text
 kind: namespace-method
 tokens: Text.join
-sig: Text.join(parts, sep) -> str
+sig: Text.join(parts, sep) -> string
 tip: Join a list of strings with a separator.
 order: 18
 ns: Text

docs/language/text/text-length.md

@@ -18,7 +18,7 @@ Parameters:
 
 ```ludic
 program NameWidth {
-  var label: str = "player one"
+  var label: string = "player one"
 
   handler Draw phase Render {
     let width = Text.length(label) * 6   # 6 px per glyph

docs/language/text/text-lower.md

@@ -4,7 +4,7 @@ name: Text.lower
 category: text
 kind: namespace-method
 tokens: Text.lower
-sig: Text.lower(s) -> str
+sig: Text.lower(s) -> string
 tip: A lowercased copy of a string.
 order: 12
 ns: Text

docs/language/text/text-pad_left.md

@@ -4,7 +4,7 @@ name: Text.pad_left
 category: text
 kind: namespace-method
 tokens: Text.pad_left
-sig: Text.pad_left(s, width) -> str
+sig: Text.pad_left(s, width) -> string
 tip: Pad with spaces on the left to a width.
 order: 15
 ns: Text

docs/language/text/text-pad_right.md

@@ -4,7 +4,7 @@ name: Text.pad_right
 category: text
 kind: namespace-method
 tokens: Text.pad_right
-sig: Text.pad_right(s, width) -> str
+sig: Text.pad_right(s, width) -> string
 tip: Pad with spaces on the right to a width.
 order: 16
 ns: Text

docs/language/text/text-repeat.md

@@ -4,7 +4,7 @@ name: Text.repeat
 category: text
 kind: namespace-method
 tokens: Text.repeat
-sig: Text.repeat(s, n) -> str
+sig: Text.repeat(s, n) -> string
 tip: A string repeated n times.
 order: 14
 ns: Text

docs/language/text/text-replace.md

@@ -4,7 +4,7 @@ name: Text.replace
 category: text
 kind: namespace-method
 tokens: Text.replace
-sig: Text.replace(s, from, to) -> str
+sig: Text.replace(s, from, to) -> string
 tip: Replace every occurrence of a substring.
 order: 19
 ns: Text

docs/language/text/text-slice.md

@@ -4,7 +4,7 @@ name: Text.slice
 category: text
 kind: namespace-method
 tokens: Text.slice
-sig: Text.slice(s, a, b) -> str
+sig: Text.slice(s, a, b) -> string
 tip: A substring covering bytes [a, b).
 order: 2
 ns: Text
@@ -20,7 +20,7 @@ Parameters:
 
 ```ludic
 program FirstWord {
-  var line: str = "hello world"
+  var line: string = "hello world"
 
   handler Split phase Update {
     let space = Text.index_of(line, " ")   # 5

docs/language/text/text-split.md

@@ -4,14 +4,14 @@ name: Text.split
 category: text
 kind: namespace-method
 tokens: Text.split
-sig: Text.split(s, sep) -> []str
+sig: Text.split(s, sep) -> []string
 tip: Split a string on a separator into a list.
 order: 17
 ns: Text
 member: split
 ---
 
-Splits <code>s</code> at every occurrence of the non-empty separator <code>sep</code> and returns the pieces as a <code>[]str</code> — the inverse of <code>Text.join</code>. Adjacent separators yield empty pieces, and a string with no separator returns a one-element list holding the whole string. Use it to parse CSV rows, command arguments, or delimited save data.
+Splits <code>s</code> at every occurrence of the non-empty separator <code>sep</code> and returns the pieces as a <code>[]string</code> — the inverse of <code>Text.join</code>. Adjacent separators yield empty pieces, and a string with no separator returns a one-element list holding the whole string. Use it to parse CSV rows, command arguments, or delimited save data.
 
 ```ludic
 program Demo {

docs/language/text/text-starts_with.md

@@ -19,7 +19,7 @@ Parameters:
 
 ```ludic
 program Command {
-  var input: str = "/say hello"
+  var input: string = "/say hello"
 
   handler Parse phase Update {
     if Text.starts_with(input, "/say ") {

docs/language/text/text-to_int.md

@@ -18,7 +18,7 @@ Parameters:
 
 ```ludic
 program ParseAmount {
-  var typed: str = "250"
+  var typed: string = "250"
 
   handler Apply phase Update {
     let gold = Text.to_int(typed)   # 250

docs/language/text/text-trim.md

@@ -4,7 +4,7 @@ name: Text.trim
 category: text
 kind: namespace-method
 tokens: Text.trim
-sig: Text.trim(s) -> str
+sig: Text.trim(s) -> string
 tip: A copy with surrounding whitespace removed.
 order: 13
 ns: Text

docs/language/text/text-upper.md

@@ -4,7 +4,7 @@ name: Text.upper
 category: text
 kind: namespace-method
 tokens: Text.upper
-sig: Text.upper(s) -> str
+sig: Text.upper(s) -> string
 tip: An uppercased copy of a string.
 order: 11
 ns: Text