Pi skill integration, CLI polish, --fix flag, config file support

- SKILL.md: Proper Agent Skills frontmatter with name/description
- pi-extension.ts: Pi extension registering 4 custom tools
  (project_map_init/patch/validate/reinit) with prompt snippets/guidelines
- pi-extension.ts: Auto-detects .pi-map.md files on session start, warns
  about dirty markers, injects maintenance hints before agent start
- package.json: Added pi.extensions and pi.skills entries
- CLI: Added picocolors, clean help screen, progress indicators,
  summary output with timing, colored check/warning icons
- validate.ts: Added --fix flag that regenerates directories with
  discrepancies
- config.ts: Reads .pi-project-map.json from project root with merge
  over defaults
- init.ts: Added optional verbose parameter for programmatic use

All 16 tests pass. TypeScript compiles clean. Build succeeds.

tsconfig.json

@@ -15,5 +15,5 @@
     "resolveJsonModule": true
   },
   "include": ["src/**/*"],
-  "exclude": ["node_modules", "dist"]
+  "exclude": ["node_modules", "dist", "pi-extension.ts"]
 }