feat(deepinit): add manifest-based incremental deepinit tool

[anduinnn]

Summary

• Add deepinit_manifest MCP tool with 3 actions: diff, save, check
• Tracks directory file lists so subsequent /deepinit runs only regenerate AGENTS.md for changed directories (~90% token savings)
• Security hardening: symlink containment, inode loop detection, depth/count limits
• 44 test cases covering all actions, edge cases, and security scenarios

Changes

• src/tools/deepinit-manifest.ts — Core tool implementation (scan, diff, load, save, check)
• src/tools/__tests__/deepinit-manifest.test.ts — 44 test cases
• src/mcp/omc-tools-server.ts — Tool registration with DEEPINIT category
• src/constants/names.ts — DEEPINIT tool category constant
• src/lib/worktree-paths.ts — DEEPINIT_MANIFEST path constant

Test plan

• All 44 unit tests passing (npx vitest run src/tools/__tests__/deepinit-manifest.test.ts)
• tsc --noEmit clean
• Manual verification: run deepinit_manifest with action=check, action=save, action=diff

Closes #1719

[Yeachan-Heo]

CI failed — omc-tools-server.test.ts expects 41 tools but got 42. You added a new tool but didn't update the tool count assertions.

Please update src/__tests__/omc-tools-server.test.ts:

• omcToolNames → should export expected tools total: change expected count from 41 to 42
• getOmcToolNames → update the expected counts in the filter tests accordingly (should return all tools, filter out LSP, filter out AST, filter out python_repl, filter out skills)

After fixing, push to the same branch and CI should pass.

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[repo owner's gaebal-gajae (clawdbot) 🦞]