v0.3.0: structural refactor — go:embed templates, server split, domain rename

- Migrate all 7 HTML templates + CSS from Go string constants to individual
  go:embed files in internal/web/templates/ (templates.go: 2150→35 lines)
- Split server.go into auth.go, handlers.go, funcmap.go (server.go: 540→120 lines)
- Rename controller subdomain from dashboard.* to felhom.* in Traefik labels
- Update documentation (CLAUDE.md, README.md, CONTEXT.md)

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

CLAUDE.md

@@ -38,7 +38,14 @@ E:\git\deploy-felhom-compose\     (or /e/git/deploy-felhom-compose/ in Git Bash)
 │   │   ├── sync/                  # Git sync — periodic pull of app catalog repo
 │   │   ├── api/                   # REST API endpoints
 │   │   ├── system/                # System info (memory, disk)
-│   │   └── web/                   # Dashboard UI (embedded HTML/CSS templates)
+│   │   └── web/                   # Dashboard UI
+│   │       ├── server.go          # Server struct, routing, static serving
+│   │       ├── auth.go            # Session auth, login/logout handlers
+│   │       ├── handlers.go        # Page handlers (dashboard, stacks, deploy, etc.)
+│   │       ├── funcmap.go         # Template function map
+│   │       ├── embed.go           # go:embed directive for templates
+│   │       ├── templates.go       # Felhom logo SVG constant
+│   │       └── templates/         # go:embed HTML/CSS files (Hungarian UI)
 │   ├── Dockerfile
 │   ├── Makefile
 │   └── go.mod
@@ -148,8 +155,8 @@ manually via the dashboard "Sablonok frissítése" button.
 
 - **Language:** Go 1.22+
 - **Web framework:** stdlib `net/http` + `html/template` (no frameworks)
-- **Templates:** Embedded as Go string constants in `templates.go` (Hungarian UI)
-- **CSS:** Single embedded const in `templates.go` (no external CSS files)
+- **Templates:** go:embed HTML files in `internal/web/templates/` (Hungarian UI)
+- **CSS:** go:embed CSS file in `internal/web/templates/style.css`
 - **Auth:** bcrypt password hash + session cookies
 - **Container orchestration:** Docker Compose via CLI (`docker compose up -d`)
 - **Reverse proxy:** Traefik (separate stack, managed by controller)