[codegen] annotate member-access expressions with class/interface types

[cs01]

Before

The typeOf cache held only primitive literals and variable-read results (from #660/#661). Member-access expressions like `obj.field` fell through to live-resolution at every codegen site.

After

`member_access` expressions whose resolved type is a concrete class or interface are now annotated. Codegen sites reading `typeOf(obj.field)` get the cached answer.

Description

Step 2 of #658 gate-loosening plan.

Same source-kind filter as step 1 (`class` | `interface`). Unfiltered annotation (including primitives/arrays/Map/Set) segfaulted Stage 1 self-hosting; filtering to the shapes whose LLVM representation is fully determined by the base name sidesteps the symbol-table disagreement.

Verification

• `npm run verify` (Stage 0 + Stage 1 + Stage 2 self-hosting + full test suite): PASSED

Refs #658.

[github-actions]

Benchmark Results (Linux x86-64)

Benchmark	C	ChadScript	Go	Node	Place
Fibonacci	0.815s	0.767s	1.565s	3.228s	🥇
Hash Map Lookup	0.092s	0.063s	0.091s	0.124s	🥇
Binary Trees	1.355s	1.256s	2.758s	1.171s	🥈
Cold Start	0.8ms	0.9ms	1.2ms	27.2ms	🥈
File I/O	0.118s	0.096s	0.086s	0.208s	🥈
JSON Parse/Stringify	0.037s	0.053s	0.178s	0.134s	🥈
N-Body Simulation	1.677s	2.118s	2.208s	2.389s	🥈
Regex Match	0.016s	0.005s	0.021s	0.005s	🥈
SQLite	0.053s	0.366s	0.484s	0.411s	🥈
Monte Carlo Pi	0.390s	0.411s	0.405s	2.251s	🥉
Quicksort	0.215s	0.247s	0.213s	0.263s	🥉
Sieve of Eratosthenes	0.016s	0.028s	0.019s	0.038s	🥉
String Manipulation	0.008s	0.020s	0.019s	0.038s	🥉
Matrix Multiply	0.465s	0.998s	0.567s	0.379s	#4

CLI Tool Benchmarks

Benchmark	ChadScript	grep	node	xxd	Place
Hex Dump	0.650s	—	0.966s	0.133s	🥈
Recursive Grep	0.022s	0.011s	0.107s	—	🥈