refactor: rename project videnc-vibe -> av1dae

Rename the Go module, the cmd/ entrypoint dir, the binary, the default config
dir (~/.config/av1dae/), the Docker image/compose service, and all docs and
the dashboard wordmark. No behavioral change — import paths and identifiers
only.

docker-compose.yml

@@ -1,7 +1,7 @@
 services:
-  videnc:
+  av1dae:
     build: .
-    container_name: videnc-vibe
+    container_name: av1dae
     restart: unless-stopped
     # Cap CPU/RAM so a long SVT-AV1 encode can't starve the host. Tune to taste.
     # `podman compose` honors deploy.resources; `podman-compose` (python) wants