refactor: P2 cleanup — extract shared utils, inline trivial files, safety guards

[thymikee]

Summary

Complete P2 DRY violations and cleanup from codebase review.

• P2-1: Extract mergeDefinedFlags to shared utils/merge-flags.ts
• P2-2: Inline trivial single-use files (json-input, session-routing, lease-context, dispatch-payload, context, etc.)
• P2-3: Merge upload-client.ts into daemon-client.ts
• P2-4: Extract generic parsing utilities from client-normalizers.ts to utils/parsing.ts
• P2-5: Unify request-router handler dispatch (loop instead of if-chain)
• P2-6: Unify daemon-client transport timeout/error handling
• P2-7: Merge recording-telemetry.ts into recording-gestures.ts
• P2-8: Extract repeated handler boilerplate into handler-utils.ts
• P2-9: Add bounded cleanup for request-cancel.ts maps
• P2-10: Add .unref() to upload-registry.ts timers
• P2-11: Add error handling to async IIFE in transport.ts

Test plan

• npx tsc -p tsconfig.json --noEmit passes
• npx vitest run — all tests pass

🤖 Generated with Claude Code

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