feat(release): decouple distribution from the source repo

Publish every release to the public OwnCord-releases repo with a full
source snapshot (AGPL section 6 for binary recipients), and make the
updater's repo coordinates configurable (github.owner/github.repo),
defaulting to OwnCord-releases. Both the server self-update and the
/client-update chain follow the new default, so deployed servers keep
updating after the source repo goes private.

The publish step fails closed: a private source repo with no
RELEASES_REPO_TOKEN aborts the release instead of silently shipping
binaries with no public source or update feed.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

docs/server-configuration.md

@@ -66,6 +66,8 @@ Configuration is loaded in three layers (later layers override earlier ones):
 | Key | Type | Default | Description |
 |-----|------|---------|-------------|
 | `github.token` | string | `""` | Optional GitHub API token for higher rate limits on update checks (5000 req/hr vs 60) |
+| `github.owner` | string | `"J3vb"` | Owner of the GitHub repository server and client updates are fetched from |
+| `github.repo` | string | `"OwnCord-releases"` | Public releases repository. Must stay publicly readable — both the server self-update and the client auto-update chain fetch release assets from it |
 
 ### Event Persistence (`event_persistence`)
 
@@ -178,6 +180,8 @@ voice:
 
 github:
   token: ""                        # optional GitHub PAT for update check rate limits
+  owner: "J3vb"                    # update source repo owner
+  repo: "OwnCord-releases"         # public releases repo (binaries + source snapshots)
 
 # Event persistence (tiered reconnect replay)
 event_persistence: