feat(infra): Migrate from Harbor to Gitea Packages registry

BREAKING CHANGE: Container registry changed from Harbor to Gitea Packages

Changes:
- Update .woodpecker.yml to push to git.mosaicstack.dev instead of reg.mosaicstack.dev
- Change secret names: harbor_username/harbor_password → gitea_username/gitea_token
- Update docker-compose.prod.yml image references
- Update all three images: api, web, postgres

Registry Migration:
- Old: reg.mosaicstack.dev (Harbor)
- New: git.mosaicstack.dev (Gitea Packages)
- Old: reg.diversecanvas.com (Harbor)
- New: git.mosaicstack.dev (Gitea Packages)

Manual Steps Required:
1. Create Gitea personal access token with 'read:package' and 'write:package' scopes
2. Add Woodpecker secrets:
   - gitea_username: Your Gitea username
   - gitea_token: Personal access token from step 1
3. Test build pipeline
4. Delete old Harbor secrets after validation

Related: ADR-001 in jarvis-brain
See: jarvis-brain/docs/migrations/harbor-to-gitea-packages.md

docker-compose.prod.yml

@@ -1,7 +1,7 @@
-# Production Docker Compose - Uses pre-built images from Harbor
+# Production Docker Compose - Uses pre-built images from Gitea Packages
 #
 # Prerequisites:
-#   - Images built and pushed to reg.diversecanvas.com/mosaic/*
+#   - Images built and pushed to git.mosaicstack.dev/mosaic/*
 #   - .env file configured with production values
 #
 # Usage:
@@ -16,7 +16,7 @@ services:
   # PostgreSQL Database
   # ======================
   postgres:
-    image: reg.diversecanvas.com/mosaic/postgres:latest
+    image: git.mosaicstack.dev/mosaic/postgres:latest
     container_name: mosaic-postgres
     restart: unless-stopped
     environment:
@@ -70,7 +70,7 @@ services:
   # Mosaic API
   # ======================
   api:
-    image: reg.diversecanvas.com/mosaic/api:latest
+    image: git.mosaicstack.dev/mosaic/api:latest
     container_name: mosaic-api
     restart: unless-stopped
     environment:
@@ -121,7 +121,7 @@ services:
   # Mosaic Web
   # ======================
   web:
-    image: reg.diversecanvas.com/mosaic/web:latest
+    image: git.mosaicstack.dev/mosaic/web:latest
     container_name: mosaic-web
     restart: unless-stopped
     environment: