feat(launcher): Gitea-backed alpha update feed replaces the GitHub Releases source

The launcher reported "no client available" because its update source was
pinned to a GitHub Releases manifest in a PRIVATE repo — nothing anonymous
could ever be fetched from it. Switch the feed to the PUBLIC Gitea repo so a
friend needs no account, and add the two commands that publish it.

- ReleaseManifestClient.ProductionManifestUri now points at
  git.snakedesert.se/erik/acdream raw on the `dist` branch. No update
  machinery changed: the existing strict reader already accepts any HTTPS
  manifest, so this is a URL swap plus a build script.

- tools/publish-bin.ps1 publishes the payloads into /bin and writes
  bin/manifest.json (schema v1, SHA-256 + size per artifact):
    client-win-x64.zip    AcDream.App + acdream-headless
    launcher-win-x64.zip  acdream-launcher + co-deployed acdream-bake
  Stamps InformationalVersion ONLY — never -p:Version, which also rewrites
  project-reference versions inside the committed packages.<rid>.lock.json
  files and churned every one of them with a throwaway build stamp.

- tools/publish-dist.ps1 pushes /bin to the Gitea-only `dist` branch from a
  throwaway worktree, leaving the developer's checkout, index, and HEAD
  untouched. It refuses a GitHub remote outright.

Why `dist` and not main: the launcher payload is ~103 MB because the launcher
and its co-deployed bake CLI are each self-contained single files (deliberate,
see AcDream.Launcher.csproj). GitHub hard-rejects files over 100 MB, and all
three refs currently track main, so payloads on main would break every GitHub
push. `dist` is a single-commit orphan branch that each publish REPLACES, so
superseded builds never accumulate. /bin stays gitignored repo-wide and is
force-added only on that branch.

Verified live: manifest and both payloads serve anonymously over HTTPS, and a
downloaded client payload matches its declared SHA-256 and size byte for byte.

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

tests/AcDream.Launcher.Core.Tests/Updates/ReleaseTransportTests.cs

@@ -91,11 +91,16 @@ public sealed class ReleaseManifestClientTests
 
         Assert.Equal("2.1.0", manifest.Version.Value);
         Assert.Equal(client.LongLength, manifest.RequireClient("win-x64").Size);
-        Assert.Equal("eriknihlen", ReleaseManifestClient.GitHubOwner);
-        Assert.Equal("acdream", ReleaseManifestClient.GitHubRepository);
+        // Alpha distribution feed: the PUBLIC Gitea repo's `dist` branch
+        // (GitHub stays private, so its Releases feed cannot serve anonymous
+        // friend installs, and its 100 MB per-file limit could not carry the
+        // launcher payload). tools/publish-bin.ps1 writes the payloads and
+        // tools/publish-dist.ps1 pushes that branch — all three must agree on
+        // this URL.
         Assert.Equal(
-            "https://github.com/eriknihlen/acdream/releases/latest/download/manifest.json",
+            "https://git.snakedesert.se/erik/acdream/raw/branch/dist/bin/manifest.json",
             ReleaseManifestClient.ProductionManifestUri.AbsoluteUri);
+        Assert.Equal(Uri.UriSchemeHttps, ReleaseManifestClient.ProductionManifestUri.Scheme);
     }
 
     [Theory]