feat(testing): built-in test blocks + expect assertions, auto-run with pass/fail (#12)

A `test "name" { ... }` top-level block is discovered automatically and run by a
synthetic runner @main — no `entry` to write, nothing to register. Inside a test,
expect(cond) / expect_eq(a, b) / expect_near(a, b, tol) assert; on failure they
print `file:line: <what> failed (got G, want W)` and set a per-test fail flag but
keep going, so one run reports every failure. The runner prints `ok   - name` /
`FAIL - name` per test, a `== N passed, M failed ==` summary, and exits non-zero
if any test failed — so `ludic spec_test.ludic` drops straight into bin/x and CI.
expect_near carries the tolerance fixed-point / accumulated-integer game math need.

Frontend: new `test` keyword (parse_test -> N_TEST, collected in g_tests) and the
call node now carries its source line for the file:line messages. Backend:
emit_test_runner synthesises @fn__test_i bodies + the runner @main; the expect*
builtins lower to a branch-print-flag tail (emit_expect_fail). g_src_name (set in
main from the input path) supplies the filename. The compiler's own source has no
`test` blocks, so its self-compiled IR is unchanged and the C-free fixpoint holds.

- `test` wired into the vocabulary (ludic_syntax.h, JetBrains lexer, TextMate
  grammar) and documented (docs/language/testing/)
- examples/library/testing.ludic: a passing spec, guarded by a new spec_case in
  the regression suite (build, run, require exit 0 + the expected summary)

Coverage instrumentation (the biggest lift in #12) is left as a follow-up.

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

tools/editors/jetbrains/src/main/kotlin/io/ludic/ide/LudicTokens.kt

@@ -42,7 +42,7 @@ object LudicTokens {
 object LudicVocabulary {
     val DECL = setOf(
         "program", "import", "property", "model", "enum", "ui",
-        "const", "var", "function", "extern", "handler", "entry", "event", "scene"
+        "const", "var", "function", "extern", "handler", "entry", "event", "scene", "test"
     )
     val CLAUSE = setOf(
         "phase", "query", "on", "cancellable", "public", "layer", "start"

tools/editors/shared/ludic.tmLanguage.json

@@ -176,7 +176,7 @@
         { "name": "keyword.operator.logical.ludic", "match": "\\b(and|or|not)\\b" },
         { "name": "keyword.other.clause.ludic", "match": "\\b(phase|query|on)\\b" },
         { "name": "keyword.other.ludic", "match": "\\b(import|extern)\\b" },
-        { "name": "storage.type.ludic", "match": "\\b(program|property|model|enum|ui|const|var|let|function|handler|entry|state)\\b" },
+        { "name": "storage.type.ludic", "match": "\\b(program|property|model|enum|ui|const|var|let|function|handler|entry|state|test)\\b" },
         { "name": "support.type.primitive.ludic", "match": "\\b(int|long|fixed|bool|entity|string|pointer|byte|words|fixeds|pointers|Vector|void)\\b" },
         { "name": "constant.language.boolean.ludic", "match": "\\b(true|false|null)\\b" },
         { "name": "constant.language.phase.ludic", "match": "\\b(Start|Input|FixedUpdate|Update|LateUpdate|Render)\\b" }

tools/editors/vscode/syntaxes/ludic.tmLanguage.json

@@ -176,7 +176,7 @@
         { "name": "keyword.operator.logical.ludic", "match": "\\b(and|or|not)\\b" },
         { "name": "keyword.other.clause.ludic", "match": "\\b(phase|query|on)\\b" },
         { "name": "keyword.other.ludic", "match": "\\b(import|extern)\\b" },
-        { "name": "storage.type.ludic", "match": "\\b(program|property|model|enum|ui|const|var|let|function|handler|entry|state)\\b" },
+        { "name": "storage.type.ludic", "match": "\\b(program|property|model|enum|ui|const|var|let|function|handler|entry|state|test)\\b" },
         { "name": "support.type.primitive.ludic", "match": "\\b(int|long|fixed|bool|entity|string|pointer|byte|words|fixeds|pointers|Vector|void)\\b" },
         { "name": "constant.language.boolean.ludic", "match": "\\b(true|false|null)\\b" },
         { "name": "constant.language.phase.ludic", "match": "\\b(Start|Input|FixedUpdate|Update|LateUpdate|Render)\\b" }