refactor(runtime,packages,examples): named constants, package enums, idiom sweep

- runtime: HEADLESS_FRAME_PATH, STICK_DEADZONE / STICK_LEFT_X/Y, key and
  byte codes as char literals throughout (`k == 'w'`, `fill(rt_map, ' ', …)`)
- ludic.gameplay/stats: drop the duplicate `stat_field` (it answered "atk"
  for every build stat); Stats.base uses stats_field_name
- ludic.shooter: compare aim modes and fire patterns with AimMode.* and
  WeaponPattern.* instead of raw ints; STICK_RIGHT_X/Y
- ludic.npcai: DecisionMade / brain_set_state use AiState.*
- examples/games/menu.ludic uses Font.load / Ui.* with FONT_PATH and
  BACKDROP named; strings.ludic header says what it prints
- whole tree: `x = x + 1` → `x += 1` (single-term right-hand sides only),
  `0 - x` → `-x`, ASCII codes → char literals; every .ludic and every
  ```ludic fence reformatted with the fixed formatter (whitespace only)

Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>

runtime/native/http.ludic

@@ -47,7 +47,7 @@ function http_init() -> void {
     h_used[i] = 0;  h_native[i] = 0;  h_sent[i] = 0;  h_res[i] = 0
     h_status[i] = 0;  h_blen[i] = 0
     h_req[i] = null;  h_body[i] = null;  h_hdr[i] = null
-    i = i + 1
+    i += 1
   }
   h_ready = true
 }
@@ -62,9 +62,9 @@ function http_slot_alloc() -> int {
       h_req[i] = null;  h_body[i] = null;  h_hdr[i] = null
       return i
     }
-    i = i + 1
+    i += 1
   }
-  return 0 - 1
+  return -1
 }
 
 function http_valid(h: int) -> bool {
@@ -77,7 +77,7 @@ function http_valid(h: int) -> bool {
 function http_cstr_len(p: pointer) -> int {
   if p == null { return 0 }
   var n = 0
-  while p[n] != 0 { n = n + 1 }
+  while p[n] != 0 { n += 1 }
   return n
 }
 
@@ -147,9 +147,9 @@ function http_poll(h: int) -> int {
   if not http_valid(h) { return 0 }
   let s = h - 1
   if h_native[s] == 0 { return h_status[s] }        # a parsed handle is ready immediately
-  if h_sent[s] == 0 { return 0 - 1 }
+  if h_sent[s] == 0 { return -1 }
   if h_res[s] == 1 { return h_status[s] }
-  if hs_done(s) == 0 { return 0 - 1 }
+  if hs_done(s) == 0 { return -1 }
   # first time we see it finished: cache the fields off the worker.
   h_status[s] = hs_status(s)
   h_body[s]   = hs_body(s)
@@ -204,13 +204,13 @@ function http_slice_dup(src: pointer, a: int, b: int) -> pointer {
   if n < 0 { n = 0 }
   let out = bytes(n + 1)
   var i = 0
-  while i < n { out[i] = src[a + i];  i = i + 1 }
+  while i < n { out[i] = src[a + i];  i += 1 }
   out[n] = 0
   return out
 }
 
-function http_is_digit(c: int) -> bool { return (c >= 48) and (c <= 57) }
-function http_lower(c: int) -> int { if (c >= 65) and (c <= 90) { return c + 32 };  return c }
+function http_is_digit(c: int) -> bool { return (c >= '0') and (c <= '9') }
+function http_lower(c: int) -> int { if (c >= 'A') and (c <= 'Z') { return c + 32 };  return c }
 
 # Parse a raw HTTP/1.1 response (status line + headers + blank line + body) into
 # a ready handle. Useful for cached/custom transports and offline tests.
@@ -221,20 +221,20 @@ function http_parse(resp: pointer, len: int) -> int {
 
   # status: the token after the first space on the status line.
   var i = 0
-  while (i < len) and (resp[i] != 32) { i = i + 1 }   # skip "HTTP/1.1"
-  while (i < len) and (resp[i] == 32) { i = i + 1 }   # skip the space(s)
+  while (i < len) and (resp[i] != ' ') { i += 1 }   # skip "HTTP/1.1"
+  while (i < len) and (resp[i] == ' ') { i += 1 }   # skip the space(s)
   var st = 0
-  while (i < len) and http_is_digit(resp[i]) { st = (st * 10) + (resp[i] - 48);  i = i + 1 }
+  while (i < len) and http_is_digit(resp[i]) { st = (st * 10) + (resp[i] - 48);  i += 1 }
   h_status[s] = st
 
   # header/body split at the first CRLFCRLF.
-  var split = 0 - 1
+  var split = -1
   var j = 0
   while (j + 3) < len {
-    if (resp[j] == 13) and (resp[j + 1] == 10) and (resp[j + 2] == 13) and (resp[j + 3] == 10) {
+    if (resp[j] == '\r') and (resp[j + 1] == '\n') and (resp[j + 2] == '\r') and (resp[j + 3] == '\n') {
       split = j
       j = len
-    } else { j = j + 1 }
+    } else { j += 1 }
   }
   var hdr_end = split
   var body_start = split + 4
@@ -243,8 +243,8 @@ function http_parse(resp: pointer, len: int) -> int {
   # header block starts after the status line's CRLF.
   var hs = 0
   while (hs + 1) < len {
-    if (resp[hs] == 13) and (resp[hs + 1] == 10) { hs = hs + 2;  break }
-    hs = hs + 1
+    if (resp[hs] == '\r') and (resp[hs + 1] == '\n') { hs += 2;  break }
+    hs += 1
   }
   if hs > hdr_end { hs = hdr_end }
   h_hdr[s] = http_slice_dup(resp, hs, hdr_end)
@@ -264,17 +264,17 @@ function http_find_header(hdr: pointer, name: pointer) -> pointer {
   while i < hlen {
     # match name at the start of a line, followed by ':'.
     var k = 0
-    while (k < nlen) and ((i + k) < hlen) and (http_lower(hdr[i + k]) == http_lower(name[k])) { k = k + 1 }
-    if (k == nlen) and ((i + k) < hlen) and (hdr[i + k] == 58) {
+    while (k < nlen) and ((i + k) < hlen) and (http_lower(hdr[i + k]) == http_lower(name[k])) { k += 1 }
+    if (k == nlen) and ((i + k) < hlen) and (hdr[i + k] == ':') {
       var v = i + k + 1
-      while (v < hlen) and (hdr[v] == 32) { v = v + 1 }    # skip spaces after ':'
+      while (v < hlen) and (hdr[v] == ' ') { v += 1 }    # skip spaces after ':'
       var e = v
-      while (e < hlen) and (hdr[e] != 13) and (hdr[e] != 10) { e = e + 1 }
+      while (e < hlen) and (hdr[e] != '\r') and (hdr[e] != '\n') { e += 1 }
       return http_slice_dup(hdr, v, e)
     }
     # advance to the next line.
-    while (i < hlen) and (hdr[i] != 10) { i = i + 1 }
-    i = i + 1
+    while (i < hlen) and (hdr[i] != '\n') { i += 1 }
+    i += 1
   }
   return null
 }