Native Dagger container builds + Navidrome v0.61.1 (#330)

## Summary
- Move Dagger module from `.dagger/` to repo root (`src/blumeops/`), rename `blumeops-ci` → `blumeops`
- Replace opaque `docker_build()` with native Dagger pipelines that surface full build errors per step
- Migrate navidrome as the first container (`containers/navidrome/container.py`)
- Upgrade navidrome from v0.60.3 to v0.61.1 (major artwork overhaul, SQLite FTS5 search, server-managed transcoding)
- Add `dagger call container-version` for CI version extraction without Dockerfile parsing
- All mise tasks (`container-list`, `container-version-check`, `container-build-and-release`) updated for hybrid mode
- Legacy `docker_build()` fallback preserved for all other containers

## Motivation
When navidrome v0.61.0 added a new Go build tag (`sqlite_fts5`), `docker_build()` showed only "exit code: 1". We had to run `docker build --progress=plain` manually to find `undefined: buildtags.SQLITE_FTS5`. Native Dagger pipelines show the full error inline.

## Container build dispatch needed
After merge, dispatch container build for navidrome:
```
mise run container-build-and-release navidrome --ref 470b4bd
```

## Deploy steps
1. Wait for container build to complete
2. Back up navidrome-data PVC (non-reversible DB migrations)
3. `argocd app set navidrome --revision main && argocd app sync navidrome`
4. Verify at https://dj.ops.eblu.me

## Future
Remaining containers migrate incrementally in follow-up PRs using the same pattern.

Reviewed-on: #330

mise-tasks/container-build-and-release

@@ -54,6 +54,8 @@ def list_containers() -> None:
         if not d.is_dir():
             continue
         types = []
+        if (d / "container.py").exists():
+            types.append("dagger")
         if (d / "Dockerfile").exists():
             types.append("dockerfile")
         if (d / "default.nix").exists():
@@ -70,11 +72,12 @@ def main(
 ) -> None:
     """Trigger container build workflows via Forgejo API dispatch."""
     container_dir = Path("containers") / container
+    has_container_py = (container_dir / "container.py").exists()
     has_dockerfile = (container_dir / "Dockerfile").exists()
     has_nix = (container_dir / "default.nix").exists()
 
-    if not has_dockerfile and not has_nix:
-        typer.echo(f"Error: No Dockerfile or default.nix found in '{container_dir}'")
+    if not has_container_py and not has_dockerfile and not has_nix:
+        typer.echo(f"Error: No container.py, Dockerfile, or default.nix found in '{container_dir}'")
         typer.echo()
         list_containers()
         raise typer.Exit(1)
@@ -90,10 +93,11 @@ def main(
 
     # Show expected builds
     builds = []
-    if has_dockerfile:
-        builds.append(f"  dockerfile -> {REGISTRY}/{image}:v<version>-{short_sha}")
+    if has_container_py or has_dockerfile:
+        label = "dagger" if has_container_py else "dockerfile"
+        builds.append(f"  {label:12s} -> {REGISTRY}/{image}:v<version>-{short_sha}")
     if has_nix:
-        builds.append(f"  nix        -> {REGISTRY}/{image}:v<version>-{short_sha}-nix")
+        builds.append(f"  {'nix':12s} -> {REGISTRY}/{image}:v<version>-{short_sha}-nix")
 
     if dry_run:
         typer.echo("[dry-run mode]")