Fix CLI subagent task routing, Ctrl+C cancellation, and session restore reliability

- Construct ServerTask directly for Bedrock CLI subagents so messages route
  correctly without needing a server CreateTask upgrade
- Handle CliAgentUserQuery input type in both request translators, including
  running command context and terminal output
- Add force_cancel_all_streaming_exchanges fallback for when Ctrl+C finds no
  in-flight streams (stuck subagent / unexpected stream end)
- Cancel active conversation on Ctrl+C in agent view compose state
- Skip agent view entry when agent is tagged-in for a running command
- Set root_task_id on Bedrock requests for proper optimistic task upgrade
- Persist app state on will_terminate to avoid losing sessions
- Trust persisted CWD without is_dir() recheck (fixes network mount restore)
- Log warning instead of silently dropping tabs with unreadable root nodes

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

app/src/pane_group/mod.rs

@@ -1552,10 +1552,14 @@ impl PaneGroup {
                     });
 
                 let raw_cwd = terminal_snapshot.cwd.clone();
-                let startup_directory = terminal_snapshot
-                    .cwd
-                    .map(PathBuf::from)
-                    .filter(|path| path.is_dir());
+                // Trust the persisted CWD without re-checking is_dir(). The path
+                // was validated at save time. If the directory no longer exists at
+                // restore time (e.g. deleted, network mount unavailable), the shell
+                // bootstrap script's `cd` will fail gracefully and fall back to HOME.
+                // Previously, the is_dir() check here would discard valid paths that
+                // were temporarily unavailable (e.g. network mounts not yet mounted
+                // at startup), causing sessions to always restore to ~/.
+                let startup_directory = terminal_snapshot.cwd.map(PathBuf::from);
 
                 log::info!(
                     "[session-restore] pane=terminal raw_cwd={raw_cwd:?} \