fix: emit compile error for for...of on numeric maps instead of segfaulting

[cs01]

Problem

for (const [k, v] of numericMap) on a Map<number, number> silently generated wrong code — it called stringMapGen.generateStringMapEntries on a %Map struct (which has double* arrays, not i8**). The destructured values were treated as i8* string pointers, so any use of k or v (e.g. console.log(k)) caused a segfault.

Fix

Added a guard in generateMapEntriesForOf that checks map metadata before generating entries iteration. If the map has no metadata (numeric maps don't store mapMetadata) or the key type isn't "string", the compiler now emits a clear compile error:

file.ts:6:3: error: for...of on Map<number, *> is not supported — use Map<string, *> instead

This is consistent with method-calls.ts which already emits compile errors for numericMap.entries(), numericMap.keys(), and numericMap.values().

Test plan

• New test fixture: map-numeric-entries-error.ts (expects compile error)
• All 459 tests pass