Add a final summary log to the Spider execution to clearly indicate the results of the run.

Current Behavior:
If no new users are found (e.g., because all repositories were already visited), the Spider exits silently after processing pages, leaving the user unsure if it worked or just found nothing.

Goal:
Print a summary at the end of the run:

• Total new candidates discovered.
• Total repositories scanned vs skipped (optional but helpful).

Changes:

• Update apps/devrank/services/Spider.mjs to track cumulative stats in the state object.
• Output a summary table or message at the end of run().