refactor: restructure project layout and add install.mjs

- Move src/ → plugin/ with subdirectories:
  - plugin/core/ (business logic, models, store, permissions, utils, memory)
  - plugin/tools/ (query, resources)
  - plugin/commands/ (placeholder for slash commands)
  - plugin/hooks/ (placeholder for lifecycle hooks)
  - plugin/index.ts (wiring layer only, no business logic)
- Add install.mjs with --install, --uninstall, --openclaw-profile-path
- Add skills/ and docs/ root directories
- Move planning docs (PLAN.md, FEAT.md, AGENT_TASKS.md) to docs/
- Remove old scripts/install.sh
- Update tsconfig rootDir: src → plugin
- Update README.md and README.zh.md with new layout
- Bump version to 0.2.0
- All tests pass

plugin/core/memory/scopeMemory.ts

@@ -0,0 +1,16 @@
+export interface MemoryPort {
+  store(input: { text: string; scope: string; metadata?: Record<string, string> }): Promise<unknown>;
+  recall(input: { query: string; scope: string; limit?: number }): Promise<unknown>;
+}
+
+export class ScopeMemory {
+  constructor(private readonly memory: MemoryPort) {}
+
+  async put(scopeId: string, text: string, metadata?: Record<string, string>): Promise<unknown> {
+    return this.memory.store({ text, scope: scopeId, metadata });
+  }
+
+  async search(scopeId: string, query: string, limit = 5): Promise<unknown> {
+    return this.memory.recall({ query, scope: scopeId, limit });
+  }
+}