ci: add Gitea CI, RPM spec, license, and repo hygiene

- Add .gitea/workflows/ci.yml with fmt/clippy/test on all branches
  and SRPM build + COPR publish on version tags
- Add cortex.spec for Fedora RPM packaging
- Add GPL-3.0-or-later LICENSE file
- Add cortex.example.toml with generic hostnames; gitignore cortex.toml
- Scrub infrastructure-specific hostnames from README.md, CLAUDE.md,
  and doc comments
- Fix unused imports and clippy warnings to pass -D warnings
- Fix missing deps (bytes, reqwest, serde_json) exposed during build
- Run cargo fmt across workspace
- Update SPDX license identifier to GPL-3.0-or-later

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

crates/cortex-gateway/src/poller.rs

@@ -64,11 +64,7 @@ async fn poll_node(fleet: &CortexState, name: &str, endpoint: &str) {
 
                     node.healthy = true;
                     node.last_poll = Some(Utc::now());
-                    tracing::debug!(
-                        node = name,
-                        models = models_resp.data.len(),
-                        "poll ok"
-                    );
+                    tracing::debug!(node = name, models = models_resp.data.len(), "poll ok");
                 }
                 Err(e) => {
                     tracing::warn!(node = name, error = %e, "failed to parse /v1/models response");