Revert idle "claude foreground" filter — back to legacy 5s notify

Reverts in one combined commit:
- 9931a92 (inline pane_id + watch list into bash script)
- 6772b8d (pivot per-distro → per-pane via TILETOPIA_PANE_ID env)
- f51033a (original per-distro idle filter)

End-to-end probe never worked correctly against the real running app
even after fixing the wsl.exe-drops-positional-args bug. Probe script
ran fine in isolation but kept returning false-negative when called
through tiletopia's wsl.exe spawn. Rather than keep iterating, back
out cleanly — pane behaviour is now the original "go idle after 5s of
silence regardless of what's running."

memory.md session log notes the lessons for a future retry: don't ship
per-distro again (CLAUDE.md explicitly says multi-claude-per-distro is
the primary use case); prove the probe end-to-end before wiring into
the idle effect (a "Test probe" button in MCP panel would have caught
this in minutes).

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

src/ipc.ts

@@ -39,19 +39,6 @@ export interface SshHost {
 
 export const listDistros = (): Promise<string[]> => invoke("list_distros");
 
-/** Ask the backend whether any built-in "watched" process (currently just
- *  `claude`) is running in THIS specific pane (not just somewhere in the
- *  distro). Per-pane detection works via a `TILETOPIA_PANE_ID` env marker
- *  injected at spawn — see src-tauri/src/probe.rs. Cached per (distro,
- *  pane_id) for ~3s. Probe failures resolve to `false` (don't suppress) —
- *  better to occasionally over-notify than permanently silence. Only
- *  meaningful for WSL panes; PS + SSH should skip this. */
-export const isWatchProcessRunning = (
-  distro: string,
-  paneId: number,
-): Promise<boolean> =>
-  invoke("is_watch_process_running", { distro, paneId });
-
 export const spawnPane = (args: {
   spec: SpawnSpec;
   cols: number;