ctx-purgelisted

# Context Mode Purge Permanently deletes session data for this project. Two scopes are supported (issue #520): - **Project scope** (`scope: "project"`): wipes EVERYTHING — knowledge base, all session DB rows for every session, events markdown, and stats. - **Session scope** (`sessionId: "<id>"` or `scope: "session"`): wipes ONLY the matching session's rows + FTS5 chunks. Sibling sessions, project stats, and the FTS5 store file are preserved. ## Instructions 1. **Decide the scope first** with the user: - "Wipe just one session?" → ask for the `sessionId`. - "Wipe the whole project?" → confirm scope:'project' (this is the destructive, irreversible default). 2. **Warn the user about scope:'project'**. Everything will be deleted: - FTS5 knowledge base (all indexed content from `ctx_index`, `ctx_fetch_and_index`, `ctx_batch_execute`) - Session events DB (analytics, metadata, resume snapshots) for ALL sessions in the project - Session events markdown file - In-memory session stats + persisted stats file 3. Call the `mcp__context-mode__ctx_purge` MCP tool with the chosen parameters: - Scoped: `{ confirm: true, sessionId: "<id>" }` — implies scope:'session'. - Project: `{ confirm: true, scope: "project" }` — explicit destructive form. - Bare `{ confirm: true }` still works but emits a deprecation warning. Prefer the explicit forms. 4. Report the result to the user — the response lists exactly what was deleted and (for scoped purges) confirms that other