Close the stdio MCP lifecycle parity gap

The runtime already had stdio MCP bootstrap, initialize, tool discovery, and tool call plumbing, but the user-facing MCP tools still returned stub payloads. This wires ListMcpResources, ReadMcpResource, McpAuth, and MCP through real config-loaded MCP manager lifecycles, adds resource listing/reading support to the manager, and updates parity notes to reflect the new stdio-only coverage.\n\nConstraint: Keep scope on the MCP parity lane and avoid behavior changes in already-landed task/team/cron/bash/file tool work beyond lint-safe compile integration\nRejected: Implement remote MCP transports and browser OAuth flow now | broader than the requested parity slice\nConfidence: high\nScope-risk: moderate\nDirective: Reuse the manager-backed lifecycle for future remote transport support instead of adding new tool-local stubs\nTested: cargo fmt; cargo clippy --workspace --all-targets -- -D warnings; cargo test --workspace\nNot-tested: Live OAuth/browser auth flow; non-stdio MCP transports

rust/crates/runtime/src/task_registry.rs

@@ -103,18 +103,20 @@ impl TaskRegistry {
     }
 
     /// Look up a task by ID.
+    #[must_use]
     pub fn get(&self, task_id: &str) -> Option<Task> {
         let inner = self.inner.lock().expect("registry lock poisoned");
         inner.tasks.get(task_id).cloned()
     }
 
     /// List all tasks, optionally filtered by status.
+    #[must_use]
     pub fn list(&self, status_filter: Option<TaskStatus>) -> Vec<Task> {
         let inner = self.inner.lock().expect("registry lock poisoned");
         inner
             .tasks
             .values()
-            .filter(|t| status_filter.map_or(true, |s| t.status == s))
+            .filter(|t| status_filter.is_none_or(|s| t.status == s))
             .cloned()
             .collect()
     }
@@ -206,6 +208,7 @@ impl TaskRegistry {
     }
 
     /// Remove a task from the registry.
+    #[must_use]
     pub fn remove(&self, task_id: &str) -> Option<Task> {
         let mut inner = self.inner.lock().expect("registry lock poisoned");
         inner.tasks.remove(task_id)