[Bugfix #418] Fix architect terminal auto-restart in dashboard

[waleedkadous]

Summary

Fixes #418

Root Cause

The architect terminal already had shellper-level auto-restart configured (restartOnExit: true, restartDelay: 2000, maxRestarts: 50), but exit handling at the PtySession and Tower layers was defeating it:

1. PtySession.cleanupShellper() cleared all WebSocket clients on exit — the restarted process had no connected clients
2. Tower exit handler cleared entry.architect = undefined and deleted the DB record — the dashboard couldn't find the restarted session

The process was actually restarting at the shellper level, but was invisible to the dashboard.

Fix

Added a restartOnExit flag to PtySession that suppresses exit cleanup when auto-restart is configured:

• WebSocket clients stay connected — when the process restarts, output flows seamlessly to the dashboard
• Tower references preserved — entry.architect and DB record remain intact
• Visual indicator — writes [Process exited — restarting...] to the terminal during the restart gap
• 10-second safety timeout — if no new data arrives (e.g., max restarts exceeded), falls through to normal exit cleanup

Files changed

• pty-session.ts — Added restartOnExit property; modified shellper exit handler to suppress cleanup when set
• tower-instances.ts — Set restartOnExit = true on architect PtySession at creation
• tower-terminals.ts — Set restartOnExit = true on architect PtySession during reconciliation and on-the-fly reconnection

Test Plan

• Added 4 regression tests covering:
  • Exit event suppressed when restartOnExit is true
  • Cleanup cancelled when new data arrives (process restarted)
  • Fallback to normal cleanup when no data arrives (max restarts exceeded)
  • Default behavior unchanged when restartOnExit is false
• All 1705 existing tests pass
• TypeScript compiles cleanly
• Net diff: 128 insertions, 3 deletions (well under 300 LOC threshold)

CMAP Review

To be added after review