feat: console.log/JSON.stringify for all types, for...of on strings

[cs01]

Summary

• console.log now works on Maps, Sets, class instances, and interfaces (was [object Object] or empty)
• JSON.stringify now works on Maps (Map<string, *>) and class instances with correct boolean handling
• for...of on strings now works (for (const ch of str)) instead of compile error
• JSON.stringify on Sets gives helpful compile error with suggestion to convert to array

Details

• Map printing uses open-addressing hash table iteration (skip null slots)
• Set printing uses linear iteration
• Class instance fields: boolean stored as double in struct, converted via fcmp une
• String for-of: allocates 2-byte GC buffer per character, null-terminated
• Interface console.log delegates to JSON.stringify

Test plan

• console-log-map.ts — Map(2) { a => 1, b => 2 }
• console-log-set.ts — Set(3) { 10, 20, 30 }
• console-log-class.ts — Point {"x":10.0,"y":20.0}
• console-log-interface.ts — {"x":10.0,"y":20.0}
• json-stringify-unsupported-map.ts — Map stringify works
• json-stringify-class.ts — class instance with boolean fields
• string-for-of.ts — iterate, concat, break
• Self-hosting passes (Stage 0 + Stage 1)
• All 470 tests pass

🤖 Generated with Claude Code