Add package-map for cross-repo SCIP navigation

- Add package-map.edn mapping namespaces to their packages
- Update CI workflow to pass package-map when generating SCIP index
- Enables cross-repo navigation to clojure-tui in Sourcegraph

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

.github/workflows/scip-index.yml

@@ -43,7 +43,7 @@ jobs:
       - name: Generate SCIP index
         run: |
           cd /tmp/scip-clojure
-          clojure -M:run -p $GITHUB_WORKSPACE -o $GITHUB_WORKSPACE/index.scip
+          clojure -M:run -p $GITHUB_WORKSPACE -o $GITHUB_WORKSPACE/index.scip -m $GITHUB_WORKSPACE/package-map.edn
         env:
           CLOJURE_LSP_PATH: /usr/local/bin/clojure-lsp