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.

package-lock.json

@@ -10,6 +10,7 @@
       "license": "MIT",
       "dependencies": {
         "ignore": "^5.3.0",
+        "picocolors": "^1.1.1",
         "tree-sitter": "^0.21.0",
         "tree-sitter-go": "^0.25.0",
         "tree-sitter-python": "^0.25.0",
@@ -2860,7 +2861,6 @@
       "version": "1.1.1",
       "resolved": "https://registry.npmjs.org/picocolors/-/picocolors-1.1.1.tgz",
       "integrity": "sha512-xceH2snhtb5M9liqDsmEw56le376mTZkEX/jEb/RxNFyegNul7eNslCXP9FDj/Lcu0X8KEyMceP2ntpaHrDEVA==",
-      "dev": true,
       "license": "ISC"
     },
     "node_modules/picomatch": {