fix(c-lsp): cap expression type evaluation steps

[romanornr]

Summary

• Add a per-file expression-evaluation step budget to the C/C++ LSP resolver
• Return unknown after the budget is exhausted instead of allowing pathological expression/type lookup loops to hang indexing
• Keep the existing recursion-depth guard, but also guard the non-stack-overflow case where evaluation repeatedly walks expensive C++ expression/type-resolution paths

Why

While indexing a large Bitcoin-derived C++ codebase, one worker could hang indefinitely in c_eval_expr_type() / c_eval_expr_type_inner() during definition extraction. The minimal repro was a single C++ test file with many versionbits-style checks; GDB showed repeated C++ expression evaluation through member/type lookup rather than a crash.

This guard trades a small amount of precision in pathological files for keeping repository indexing bounded and useful.

Test plan

• make -f Makefile.cbm test -j$(nproc)
• Fresh fast index of the large C++ repro repository completed successfully after deleting its cache DB:
  • 2179 files
  • 29,766 nodes
  • ~91k edges
  • completed in ~8.6s

Related

Follow-up to #322, which fixes a separate C++ LSP crash path.