fix(ci): Replace Mozilla sccache action with token-free alternative

Replace mozilla-actions/sccache-action with a custom Forgejo-specific
implementation that eliminates GitHub token dependencies and rate limiting
issues for all contributors regardless of repository permissions.

The new action mirrors sccache binaries to the Forgejo package registry
and queries that instead of GitHub releases, maintaining identical functionality
including hostedtoolcache support.

.forgejo/actions/sccache/action.yml

@@ -2,18 +2,12 @@ name: sccache
 description: |
   Install sccache for caching builds in GitHub Actions.
 
-inputs:
-  token:
-    description: 'A Github PAT'
-    required: false
 
 runs:
   using: composite
   steps:
   - name: Install sccache
-    uses: https://github.com/mozilla-actions/sccache-action@v0.0.9
-    with:
-      token: ${{ inputs.token }}
+    uses: https://git.tomfos.tr/tom/sccache-action@v1
   - name: Configure sccache
     uses: https://github.com/actions/github-script@v7
     with: