fix(immich): name containers underscore to match runtime lifecycle code

package.stop/start/restart broke ("no containers found" / "no such object
immich_postgres") because the runtime hardcodes the immich stack's container names
as immich_server/immich_postgres/immich_redis (underscore) across 8 files
(lifecycle, health, crash-recovery, ports, config). The migration had named the
containers by app_id (hyphen), mismatching all of it.

Root cause of the earlier failed attempt: container_name was nested under an
`extensions:` block, but `app.extensions` is serde(flatten) — container_name must
be a TOP-LEVEL app key to be read by compute_container_name. Fixed: set
container_name: immich_server / immich_postgres / immich_redis at top level, and
point DB_HOSTNAME/REDIS_HOSTNAME at the underscore aliases. App ids stay hyphen
(immich/immich-postgres/immich-redis) so the catalog identity (title+icon) holds.

Manifest-only change — container names now match existing runtime references, no
code edits to the 8 files. (Deriving stack containers from manifests instead of
hardcoded lists remains a north-star follow-up.)

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

apps/immich/manifest.yml

@@ -5,8 +5,12 @@ app:
   description: Self-hosted photo and video backup with mobile apps and search.
 
   # app_id "immich" = the user-facing launcher (matches the catalog entry's title
-  # + icon). Container is named "immich"; it reaches its backends by their app_id
-  # aliases on archy-net (see DB_HOSTNAME / REDIS_HOSTNAME below).
+  # + icon). The container is named "immich_server" so it matches the runtime's
+  # existing per-app container references (lifecycle/health/crash-recovery/ports);
+  # `container_name` is a top-level app key (captured by serde(flatten) into
+  # extensions, read by compute_container_name). It reaches its backends by their
+  # underscore aliases on archy-net (DB_HOSTNAME / REDIS_HOSTNAME below).
+  container_name: immich_server
 
   container:
     image: 146.59.87.168:3000/lfg2025/immich-server:release
@@ -42,10 +46,10 @@ app:
       options: [rw]
 
   environment:
-    - DB_HOSTNAME=immich-postgres
+    - DB_HOSTNAME=immich_postgres
     - DB_USERNAME=postgres
     - DB_DATABASE_NAME=immich
-    - REDIS_HOSTNAME=immich-redis
+    - REDIS_HOSTNAME=immich_redis
     - UPLOAD_LOCATION=/usr/src/app/upload
 
   health_check: