Make browser sidecar on-demand (#44) (#50)

Closes #44. Chrome now starts on first CDP connection, tracks concurrent helpers, reaps after 300 seconds idle, preserves the named profile, and classifies reap interruptions. Shutdown stops Chrome's process group so cookie batches flush. ADR-0005 records the measured constraints and decisions. Verification: docker build, live CDP wake, graceful stop cleanup, sh -n, and go test ./... (7 packages, 3 no tests).

Reviewed-on: #50
Co-authored-by: Sulthan Zaki <sultankiki05@gmail.com>
Co-committed-by: Sulthan Zaki <sultankiki05@gmail.com>

docker-compose.yml

@@ -122,6 +122,8 @@ services:
       # The zone *name*, which is what Chrome's ICU needs — see chrome/entrypoint.sh.
       # Absent on a non-Debian host, which the entrypoint handles by falling back to UTC.
       - /etc/timezone:/etc/timezone:ro
+      # Cloudflare clearance must survive Chrome reaping and image recreation.
+      - chrome-profile:/home/chrome/profile
     # Chrome allocates shared memory per tab and dies on Docker's 64MB default.
     shm_size: '1gb'
     # Reaps zombie renderer processes, which otherwise accumulate for the
@@ -143,6 +145,7 @@ volumes:
   # declared here: undeclared means `docker compose down -v` cannot take it
   # with the rest, so the old database survives the cutover until someone
   # removes it by hand.
+  chrome-profile:
 
 networks:
   # Not `internal: true`: headless Chrome still needs outbound access to reach