Omit unused TypeScript catch exception bindings

[CaelmBleidd]

Summary

The TypeScript frontend currently emits a CaughtExceptionRef assignment even when a catch binding is never referenced. That unnecessary value can make a symbolic run fail while evaluating otherwise reachable catch code.

• Emit the caught-exception binding only when the catch block references its identifier.
• Resolve references by TypeScript symbol so a matching property name, shadowed local, or type-only mention does not create a binding; retain shorthand value references.
• Preserve the catch body and its return statements.

Validation

• npm test -- test/try.spec.ts: 12 tests passed.
• npm run typecheck: passed.
• npm run build: passed and produced the native frontend bundle.

This change is used by the prepared ICCQ unknown-call follow-up experiment. The experiment remains pinned to its original frontend revision; this PR is a clean cherry-pick onto current neo for review.

Companion runtime fixes: USVM #394, stacked on USVM #391.

[github-actions]

Test Results

  225 files  ±0    225 suites  ±0   16m 34s ⏱️ +17s
  777 tests ±0    765 ✅ ±0  12 💤 ±0  0 ❌ ±0 
2 047 runs  ±0  1 997 ✅ ±0  50 💤 ±0  0 ❌ ±0 

Results for commit 08d666c. ± Comparison against base commit ddb127d.

♻️ This comment has been updated with latest results.