fix(acp-bridge): use stable session API and cleanup

[jdmanring]

Summary

Fixes for acp-bridge stability:

• C-09: Use loadSession() for session/load instead of unstable_forkSession
• H-33: Remove redundant destructuring in bridgeClient
• H-35: Mark extractErrorCode as @internal
• L-20-L-23: Performance: regex hoisting, rate-limit dedup, telemetry alloc reduction

Files Changed

• packages/acp-bridge/src/bridge.ts
• packages/acp-bridge/src/bridgeClient.ts

Type of Change

• Bug fix
• Performance improvement
• Refactor
• New feature

Testing

• Unit tests pass
• Integration tests pass