fix: replace bash_tasks.rs with generic mcp_loose_ends scanner

- hive-ag3nt: remove bash_tasks.rs entirely; add mcp_loose_ends.rs that
  scans harness/mcp-loose-ends/*.json generically (no bash knowledge)
- hive-bash-mcp: daemon writes mcp-loose-ends/bash.json on every task
  state transition (pending/running/done/interrupted/timed_out)
- get_loose_ends: reads mcp_loose_ends::collect() instead of bash-specific code
- implements the generic mechanism from #1162

hive-bash-mcp/src/paths.rs

@@ -48,6 +48,24 @@ pub fn hyperhive_socket() -> PathBuf {
         .map_or_else(|| PathBuf::from("/run/hive/mcp.sock"), PathBuf::from)
 }
 
+/// Directory where MCP daemons write loose-end summary files for the harness.
+/// Each daemon writes `<name>.json` here; the harness scans the dir in
+/// `get_loose_ends` to surface active work from all MCPs generically.
+#[must_use]
+pub fn mcp_loose_ends_dir() -> PathBuf {
+    let base = if let Some(p) = std::env::var_os("HYPERHIVE_HARNESS_DIR") {
+        PathBuf::from(p)
+    } else {
+        let state = std::env::var("HYPERHIVE_STATE_DIR").unwrap_or_default();
+        let state_path = PathBuf::from(&state);
+        state_path
+            .parent()
+            .map(|p| p.join("harness"))
+            .unwrap_or_else(|| PathBuf::from(state))
+    };
+    base.join("mcp-loose-ends")
+}
+
 /// Full path for a task's JSON metadata file.
 #[must_use]
 pub fn task_json(id: &str) -> PathBuf {