Add Symphony release skill

.codex/skills/release/SKILL.md

@@ -0,0 +1,28 @@
+---
+name: release
+description: Cut a Symphony release by bumping the committed version, landing it, tagging the merged commit, and verifying the Burrito release workflow. Use when asked to release, tag, or retag Symphony.
+---
+
+# Release
+
+1. Start from fresh `origin/main` in a clean worktree. Never disturb unrelated
+   local changes.
+2. Pick the requested version. If none is given, use the next patch after the
+   latest `vX.Y.Z` tag.
+3. Update `elixir/mix.exs` so `version: "X.Y.Z"` matches the intended tag.
+   Search the old version and change other files only when they are true
+   release-version sources, not examples.
+4. Run `make -C elixir all`, then commit, push, create a PR, and land it.
+5. Fetch the merged `main` commit. Verify its `mix.exs` version, then create an
+   annotated tag on that exact commit:
+
+   ```sh
+   git tag -a vX.Y.Z <merged-commit> -m "Symphony vX.Y.Z"
+   git push origin vX.Y.Z
+   ```
+
+6. Watch `burrito-release` until it finishes. Verify the build, smoke, and
+   release jobs pass and that the GitHub release has all expected assets.
+
+Do not tag an uncommitted or unmerged revision. Do not move a published tag
+without explicit user approval.