chore: explicit container_name on every service, document compose v2 migration

Every service now has an explicit container_name, eliminating the
htpc-download-box_ prefix/suffix that compose derived from the directory.
Disambiguated duplicates follow type_context naming:
  postgres_resume / postgres_famapp / postgres_authentik
  minio_resume / minio_famapp
  redis_authentik

Also updates CLAUDE.md and the homelab-ssh skill to reflect:
- compose v2 (docker compose, space) replacing the old v1.27.4 standalone
- dc alias updated to docker compose
- htpc-download-box directory is now clean (legacy cruft removed)

Server-side migration steps (docker-compose-plugin apt install, alias
update, Docker Engine upgrade, old binary removal) are documented in
the session but not yet applied — run apply-compose.ps1 -Compose after
completing them.

docker-compose.yml

@@ -3,6 +3,7 @@ services:
   # FOUNDRY VTT
   # ============================================================
   foundry:
+    container_name: foundry
     image: felddy/foundryvtt:latest
     hostname: valhalla-primary
     init: true
@@ -29,6 +30,7 @@ services:
       - "30000:30000"
 
   foundry2:
+    container_name: foundry2
     image: felddy/foundryvtt:latest
     hostname: valhalla-secondary
     init: true
@@ -62,6 +64,7 @@ services:
   #   - caddy-dynamicdns      (keeps DNS records current if WAN IP changes)
   # ============================================================
   caddy:
+    container_name: caddy
     image: serfriz/caddy-cloudflare-ddns:latest
     restart: unless-stopped
     networks:
@@ -404,6 +407,7 @@ services:
   # REACTIVE RESUME STACK
   # ============================================================
   postgres:
+    container_name: postgres_resume
     image: postgres:16-alpine
     restart: unless-stopped
     networks:
@@ -421,6 +425,7 @@ services:
       retries: 5
 
   resume-minio:
+    container_name: minio_resume
     image: minio/minio:latest
     restart: unless-stopped
     networks:
@@ -442,6 +447,7 @@ services:
       start_period: 30s
 
   chrome:
+    container_name: chrome
     image: ghcr.io/browserless/chromium:latest
     restart: unless-stopped
     networks:
@@ -454,6 +460,7 @@ services:
       - PRE_REQUEST_HEALTH_CHECK=true
 
   app:
+    container_name: resume
     image: amruthpillai/reactive-resume:latest
     restart: unless-stopped
     networks:
@@ -547,6 +554,7 @@ services:
       - FRESHRSS_USER=--api-password ${FRESHRSS_API_PASSWORD} --email ${FRESHRSS_EMAIL} --password ${FRESHRSS_PASSWORD} --user ginnoir
 
   vigilant:
+    container_name: vigilant
     image: ghcr.io/verifiedjoseph/vigilant:latest
     restart: unless-stopped
     environment:
@@ -590,6 +598,7 @@ services:
   # UTILITIES
   # ============================================================
   5etools:
+    container_name: 5etools
     image: ghcr.io/5etools-mirror-3/5etools-src:latest
     restart: unless-stopped
     networks:
@@ -598,6 +607,7 @@ services:
       - "9009:80"
 
   watchtower:
+    container_name: watchtower
     image: containrrr/watchtower:latest
     restart: unless-stopped
     environment:
@@ -610,6 +620,7 @@ services:
   # FAMAPP
   # ============================================================
   famapp:
+    container_name: famapp
     image: ${FAMAPP_IMAGE:-ghcr.io/ginnoir/famapp:latest}
     pull_policy: ${FAMAPP_PULL_POLICY:-always}
     restart: unless-stopped
@@ -645,6 +656,7 @@ services:
         condition: service_healthy
 
   famapp-db:
+    container_name: postgres_famapp
     image: postgres:16-alpine
     restart: unless-stopped
     networks:
@@ -662,6 +674,7 @@ services:
       retries: 5
 
   famapp-minio:
+    container_name: minio_famapp
     image: minio/minio:latest
     command: server /data --console-address ":9003"
     restart: unless-stopped
@@ -686,6 +699,7 @@ services:
   # AUTHENTIK
   # ============================================================
   authentik-server:
+    container_name: authentik_server
     image: ghcr.io/goauthentik/server:${AUTHENTIK_IMAGE_TAG:-2024.12.3}
     restart: unless-stopped
     command: server
@@ -708,6 +722,7 @@ services:
         condition: service_healthy
 
   authentik-worker:
+    container_name: authentik_worker
     image: ghcr.io/goauthentik/server:${AUTHENTIK_IMAGE_TAG:-2024.12.3}
     restart: unless-stopped
     command: worker
@@ -728,6 +743,7 @@ services:
         condition: service_healthy
 
   authentik-db:
+    container_name: postgres_authentik
     image: postgres:16-alpine
     restart: unless-stopped
     networks:
@@ -749,6 +765,7 @@ services:
       retries: 5
 
   authentik-redis:
+    container_name: redis_authentik
     image: redis:7-alpine
     restart: unless-stopped
     networks: