fix: three codegen/parser/ffi bugs (#587, #589, #591)

[cs01]

Summary

Three independent fixes, one commit each:

• codegen: arrow-literal in class ctor body emits IR with missing @ sigil on lambda reference #587 (459665de → 02aecec1 pre-rebase) — fix(codegen): arrow literal assigned to a class field inside the ctor body was emitting store i8* __lambda_N, i8** %X (missing @ sigil). Clang rejected. Fix normalizes raw __lambda_N operands to @__lambda_N at the single class-field store site in storeFieldValueDirect. 1 file, +3 LOC (src/codegen/infrastructure/assignment-generator.ts).
• parser: rejects arr[i](args) — ElementAccessExpression as callee #589 (887c76fc → 9fcf31a8 pre-rebase) — fix(parser): CallExpression visitor now accepts ElementAccessExpression as a callee alongside CallExpression/ParenthesizedExpression. Unblocks parsing arr[i](args) dispatch-table shapes (codegen still needs function-pointer array indirect-call support to run end-to-end; that's tracked separately — the parser no longer rejects the shape). 1 file, +1/-1 LOC (src/parser-ts/handlers/expressions.ts).
• ffi: NULL char* does not reliably round-trip to empty string in TS #591 (d50c5199 → 25693fe1 pre-rebase) — fix(ffi): declare function returning a char* now round-trips NULL as the empty string. Added a select i1 (icmp eq ptr null), empty_str, result coercion at the FFI call return for declare-function i8* returns, so if (someBridge() === "") works without per-bridge _is_* probes. 1 file, +12 LOC (src/codegen/expressions/calls.ts).

Before / After

#587

class Foo {
  cb: (x: number) => number;
  constructor() { this.cb = (x) => x * 2; }
}

• Before: store i8* __lambda_0, i8** %5 → clang error: expected value token
• After: store i8* @__lambda_0, i8** %5 → compiles and calls correctly.

#589

const fns = [doubler, plusOne];
const a = fns[0](10);

• Before: parser throws Unsupported call expression: ElementAccessExpression.
• After: parser lowers to a method_call with method: "" just like existing paren/IIFE-callee shapes; downstream semantic layer now returns the real "IIFE not supported" error, making the function-array codegen gap visible and addressable as a separate follow-up.

#591

declare function getenv(name: string): string;
const v = getenv("__DOES_NOT_EXIST__");
if (v === "") { /* ok — was unreachable before */ }

• Before: NULL char* fell into the null-vs-string branch of the === strcmp lowering and produced false (bothNull was false because "" is a real string).
• After: NULL is coerced to the interned empty string at the FFI return, so v === "" is true.

Test files added

• tests/fixtures/classes/class-arrow-field-in-ctor.ts (codegen: arrow-literal in class ctor body emits IR with missing @ sigil on lambda reference #587)
• tests/fixtures/edge-cases/call-element-access-callee.ts (parser: rejects arr[i](args) — ElementAccessExpression as callee #589 — compile-error fixture asserting the parser now reaches the IIFE semantic error)
• tests/fixtures/edge-cases/ffi-null-string-to-empty.ts (ffi: NULL char* does not reliably round-trip to empty string in TS #591)

Verify

Full npm run verify passed on this branch before opening the PR:

• Stage 0: native compiler built, smoke test passed
• Stage 1 self-host: built + smoke test passed
• Stage 2 self-host: built + smoke test passed (bit-exact oracle)
• All fixture tests passed

Test plan

• CI green on npm run verify
• CI green on npm test (fixture suite picks up the three new tests)
• Self-host stages 1 + 2 still produce bit-exact binaries

[github-actions]

Benchmark Results (Linux x86-64)

Benchmark	C	ChadScript	Go	Node	Place
Cold Start	0.8ms	0.7ms	1.1ms	26.8ms	🥇
Fibonacci	0.725s	0.723s	1.430s	2.858s	🥇
Hash Map Lookup	0.099s	0.063s	0.092s	0.126s	🥇
Binary Trees	1.489s	1.477s	3.000s	1.287s	🥈
JSON Parse/Stringify	0.032s	0.044s	0.178s	0.134s	🥈
Matrix Multiply	0.432s	0.458s	0.463s	0.493s	🥈
Monte Carlo Pi	0.424s	0.430s	0.454s	1.473s	🥈
N-Body Simulation	1.430s	1.855s	1.947s	2.273s	🥈
Regex Match	0.014s	0.004s	0.021s	0.004s	🥈
SQLite	0.046s	0.329s	0.485s	0.422s	🥈
File I/O	0.070s	0.074s	0.072s	0.229s	🥉
Quicksort	0.177s	0.230s	0.203s	0.267s	🥉
Sieve of Eratosthenes	0.029s	0.041s	0.038s	0.056s	🥉
String Manipulation	0.008s	0.018s	0.017s	0.036s	🥉

CLI Tool Benchmarks

Benchmark	ChadScript	grep	node	xxd	Place
Hex Dump	0.474s	—	1.012s	0.070s	🥈
Recursive Grep	0.012s	0.007s	0.101s	—	🥈