refactor(codegen): drop redundant resolveExpressionType fallback in variable-allocator

[cs01]

Summary

• Removes a dead fallback in variable-allocator.ts:745-748 where typeOf() returning null was followed by a second call to resolveExpressionType(). That second call was always null too, because typeOf already wraps resolveExpressionTypeRich, which wraps the base resolveExpressionType — if the base is null, rich is null, so typeOf is null.
• Drops resolveExpressionType from the VariableAllocatorContext interface entirely — last consumer removed, API surface shrinks.

User-facing effect

• No behavior change. One less redundant resolver call per variable declaration.
• Tightens the Phase-E convergence: VariableAllocatorContext is now strictly a typeOf-only consumer, so future callers can't accidentally bypass the annotator cache.

Test plan

• npm run verify — full tests + 3-stage self-host green locally
• CI green

[github-actions]

Benchmark Results (Linux x86-64)

Benchmark	C	ChadScript	Go	Node	Place
Cold Start	1.0ms	0.8ms	1.2ms	26.5ms	🥇
Fibonacci	0.819s	0.765s	1.560s	3.192s	🥇
Hash Map Lookup	0.093s	0.063s	0.090s	0.112s	🥇
Binary Trees	1.391s	1.272s	2.705s	1.187s	🥈
File I/O	0.117s	0.092s	0.087s	0.204s	🥈
JSON Parse/Stringify	0.035s	0.052s	0.177s	0.137s	🥈
N-Body Simulation	1.671s	2.123s	2.221s	2.409s	🥈
Regex Match	0.016s	0.005s	0.021s	0.004s	🥈
SQLite	0.052s	0.379s	0.489s	0.413s	🥈
Monte Carlo Pi	0.389s	0.410s	0.404s	2.248s	🥉
Quicksort	0.214s	0.246s	0.213s	0.262s	🥉
Sieve of Eratosthenes	0.015s	0.028s	0.020s	0.039s	🥉
String Manipulation	0.008s	0.017s	0.016s	0.037s	🥉
Matrix Multiply	0.470s	1.005s	0.566s	0.361s	#4

CLI Tool Benchmarks

Benchmark	ChadScript	grep	node	xxd	Place
Hex Dump	0.556s	—	1.029s	0.133s	🥈
Recursive Grep	0.019s	0.009s	0.102s	—	🥈