Initial XBPS repository: fenris 0.3.5 test artifact

Test packages for XBPS proof of concept (issue #83).
Index contains v0.3.5; v0.3.6 package present for update test.

Co-authored-by: CommandCodeBot <noreply@commandcode.ai>

README.md

@@ -1,3 +1,58 @@
 # Fenris-xbps
 
-XBPS distribution repository for Fenris
+XBPS distribution repository for Fenris.
+
+## Repository Structure
+
+```
+stable/
+  x86_64/
+    fenris-<version>_1.x86_64.xbps      # Package files
+    fenris-<version>_1.x86_64.xbps.sig2  # Package signatures
+    x86_64-repodata                       # Repository index
+    x86_64-repodata.sig2                  # Repository index signature
+  keys/
+    fenris-xbps-signing.pub               # Public signing key
+```
+
+## Usage
+
+### Adding the repository
+
+```sh
+# Import the signing key
+sudo xbps-install -S https://git.bongbetic.com/xavierk/Fenris-xbps/raw/branch/stable/x86_64
+```
+
+Or manually add to `/etc/xbps.d/xbps.conf`:
+
+```
+repository=https://git.bongbetic.com/xavierk/Fenris-xbps/raw/branch/stable/x86_64
+```
+
+### Installing Fenris
+
+```sh
+sudo xbps-install -S fenris
+```
+
+### Updating Fenris
+
+```sh
+sudo xbps-install -Su fenris
+```
+
+## Signing
+
+Packages and repository metadata are signed with the Fenris XBPS signing key.
+The public key is available at `keys/fenris-xbps-signing.pub`.
+
+## Publication Mechanism
+
+1. Build the XBPS package using `xbps-create`
+2. Sign the package: `xbps-rindex --sign-pkg --privkey <key> <package>.xbps`
+3. Add to index: `xbps-rindex --add <repo-dir>/<package>.xbps`
+4. Sign the repository: `xbps-rindex --sign --privkey <key> --signedby "Fenris Packaging <packaging@bongbetic.com>" <repo-dir>`
+5. Commit and push to `stable` branch
+
+Raw URLs serve artifacts immediately without LFS indirection.