refactor: wave 1 - extract leaf modules, rename catch-all files, split index.ts hooks

- Split 25+ index.ts files into hook.ts + extracted modules
- Rename all catch-all utils.ts/helpers.ts to domain-specific names
- Split src/tools/lsp/ into ~15 focused modules
- Split src/tools/delegate-task/ into ~18 focused modules
- Separate shared types from implementation
- 155 files changed, 60+ new files created
- All typecheck clean, 61 tests pass

src/agents/AGENTS.md

@@ -61,7 +61,7 @@ agents/
 
 ## HOW TO ADD
 1. Create `src/agents/my-agent.ts` exporting factory + metadata.
-2. Add to `agentSources` in `src/agents/utils.ts`.
+2. Add to `agentSources` in `src/agents/builtin-agents.ts`.
 3. Update `AgentNameSchema` in `src/config/schema.ts`.
 4. Register in `src/index.ts` initialization.