Implement all stubs: parsePackageMap, LLM heuristics, tree-sitter AST, patch rewrite, reinit

- format.ts: Full parsePackageMap implementation with round-trip support
- llm-extract.ts: Heuristic-based extraction without LLM API (regex exports,
  imports, purpose inference from filename patterns)
- ast-extract.ts: Tree-sitter integration for TypeScript/TSX with fallback
  for other languages
- init.ts: Refactored to expose generateDirectoryMap helper, reinitPath
  delegates to initProject
- patch.ts: Small packages now use generateDirectoryMap for full rewrite
- discover.ts: Cleaned up require('fs') to use proper ES import
- Tests: 8 tests covering format round-trip and LLM heuristics
- All TypeScript compiles clean, all tests pass

src/config.ts

@@ -1,23 +1,31 @@
 export interface SkillConfig {
-  ignorePatterns: string[];
-  smallPackageThreshold: number;
-  llmModel: string;
-  contextBudget: number;
-  autoInjectPrompt: boolean;
+	ignorePatterns: string[];
+	smallPackageThreshold: number;
+	llmModel: string;
+	contextBudget: number;
+	autoInjectPrompt: boolean;
 }
 
 export const DEFAULT_CONFIG: SkillConfig = {
-  ignorePatterns: [
-    'node_modules', '.git', 'dist', 'build', 'coverage',
-    '.next', '.venv', '__pycache__', '.DS_Store', '*.log'
-  ],
-  smallPackageThreshold: 10,
-  llmModel: 'gpt-4o-mini',
-  contextBudget: 4000,
-  autoInjectPrompt: true
+	ignorePatterns: [
+		"node_modules",
+		".git",
+		"dist",
+		"build",
+		"coverage",
+		".next",
+		".venv",
+		"__pycache__",
+		".DS_Store",
+		"*.log",
+	],
+	smallPackageThreshold: 10,
+	llmModel: "gpt-4o-mini",
+	contextBudget: 4000,
+	autoInjectPrompt: true,
 };
 
 export function loadConfig(): SkillConfig {
-  // TODO: load from .pi-project-map.json or similar
-  return DEFAULT_CONFIG;
+	// TODO: load from .pi-project-map.json or similar
+	return DEFAULT_CONFIG;
 }