Initial commit: pi-project-map skill scaffolding

- Design doc with full spec (dense markdown format, hybrid AST+LLM pipeline,
  consumption model, stale data mitigation)
- Implementation plan with 6 milestones and rollout strategy
- TypeScript package structure with all source stubs
- CLI entry point, formatter, discover, init, patch, validate, extract, merge
- Pi SKILL.md with tool definitions and format documentation

SKILL.md

@@ -0,0 +1,56 @@
+# pi-project-map
+
+A Pi skill that generates and maintains a hierarchical, machine-readable analysis of a software project. Each directory gets a `.pi-map.md` file containing architectural context, exported symbols, and dependencies.
+
+## Tools
+
+### `project-map:init [root]`
+Runs a full project scan and generates `.pi-map.md` files in every directory.
+
+### `project-map:patch <file-path>`
+Updates the `.pi-map.md` for the directory containing the given file. Uses full rewrite for small packages (< 10 files) or section-level patch for larger packages.
+
+### `project-map:validate [root]`
+Checks all `.pi-map.md` files for staleness: missing files, orphaned entries, changed signatures, and dirty markers.
+
+### `project-map:reinit [path]`
+Force full re-initialization of the entire project or a specific subtree. Clears all dirty markers.
+
+## Format
+
+Each `.pi-map.md` uses dense markdown with conventions:
+
+```markdown
+# pkg/auth
+## role
+Auth layer: JWT issuance, validation, refresh. Stateless. Dep: pkg/crypto, pkg/db.
+## files
+- tokens.ts | JWT gen/val | exp: issueToken, verifyToken, refreshToken | dep: crypto/hmac, db/sessions
+- middleware.ts | HTTP auth guard | exp: requireAuth, requireRole | dep: tokens/verifyToken
+## arch
+Guard pattern on routes. Tokens short-lived (15m), refresh long-lived (7d). Rotation on every use.
+## dirty
+-
+```
+
+## Configuration
+
+Create `.pi-project-map.json` in the project root:
+
+```json
+{
+  "ignorePatterns": ["node_modules", ".git"],
+  "smallPackageThreshold": 10,
+  "llmModel": "gpt-4o-mini",
+  "contextBudget": 4000,
+  "autoInjectPrompt": true
+}
+```
+
+## Installation
+
+```bash
+npm install -g pi-project-map
+```
+
+Then add to your Pi skills configuration.