docs(#2628): update bash tool descriptions, docs, and system prompt for the todo model (trim impl details for agent)

docs/persistence.md

@@ -233,13 +233,12 @@ Under `/var/lib/hyperhive/agents/<name>/`:
     (full captured output). `hive-c0re::bash_tasks_vacuum` runs
     hourly and deletes terminal task trios older than 48 hours;
     non-terminal (still-running) tasks are never deleted by vacuum.
-  - `mcp-loose-ends/` — JSON files published by external MCP daemons
-    (e.g. `hive-bash-mcp`, `hive-matrix-mcp`) listing their active
-    loose-end summary strings. Each file is `<daemon>.json` containing
-    a JSON array of plain-text lines. Read by `get_loose_ends` to
-    surface active background work without hardcoding per-MCP
-    knowledge in the harness. Files are created/removed by the
-    external daemons themselves.
+  - `hyperhive-todos.sqlite` — loose-ends-v2 todo store. In-container
+    MCP daemons (`hive-bash-mcp`, `hive-matrix-mcp`) and `forge_notify`
+    upsert keyed todos here over the harness's in-agent socket
+    (`HIVE_AGENT_SOCKET`); the harness merges them into `get_loose_ends`
+    output and clears a row on `mark_todo_done`. Replaced the old
+    file-based `mcp-loose-ends/` scanner.
   - `hyperhive-events.sqlite` — turn-loop event log.
   - `hyperhive-turn-stats.sqlite` — per-turn timing stats.
   - `hyperhive-model` — single-line model name override file.