chore: add release skill for Claude Code (#77)

Author: zfarrell

.claude/skills/release/SKILL.md

@@ -0,0 +1,97 @@
+---
+name: release-datafusion-ducklake
+description: Prepare and publish a new release of datafusion-ducklake to crates.io
+disable-model-invocation: true
+argument-hint: "[version]"
+allowed-tools: Bash(cargo check*), Bash(cargo build*), Bash(git checkout*), Bash(git pull*), Bash(git log*), Bash(git status*), Bash(git add*), Bash(git commit*), Bash(sleep*)
+
+---
+
+# Release datafusion-ducklake
+
+Prepare and publish a new release. The user may provide a version number as `$ARGUMENTS`.
+
+## Step 1: Determine version
+
+- If a version was provided (`$ARGUMENTS`), use it. Strip a leading `v` if present (e.g. `v0.0.7` -> `0.0.7`).
+- If no version was provided, read the current version from `Cargo.toml` and suggest the next patch bump. Ask the user to confirm or provide a different version.
+
+## Step 2: Ensure clean, up-to-date main branch
+
+- Confirm we're on `main` and the working tree is clean (`git status`).
+- Pull latest: `git pull`.
+- If the branch is dirty or not on main, warn the user and stop.
+
+## Step 3: Create release branch
+
+- Create and switch to a new branch: `git checkout -b release/v{VERSION}`
+
+## Step 4: Bump version
+
+- Update `version` in `Cargo.toml` (the `[package]` section, NOT workspace members).
+- Run `cargo check` to regenerate `Cargo.lock` with the new version.
+- Verify both `Cargo.toml` and `Cargo.lock` reflect the new version.
+
+## Step 5: Update CHANGELOG.md
+
+- Read `CHANGELOG.md` and the git log since the last tag (`git log $(git describe --tags --abbrev=0)..HEAD --oneline`).
+- Add a new `## [VERSION] - YYYY-MM-DD` section at the top (below the header), categorized as Added/Changed/Fixed per Keep a Changelog format.
+- Add a comparison link at the bottom: `[VERSION]: https://github.com/hotdata-dev/datafusion-ducklake/compare/v{PREV}...v{VERSION}`
+- Ask the user to review the changelog entries before committing.
+
+## Step 6: Update README.md if needed
+
+- Check if `README.md` references a version number (e.g. in dependency examples). If so, update to the new version.
+
+## Step 7: Commit and push
+
+- Stage `Cargo.toml`, `Cargo.lock`, `CHANGELOG.md`, and `README.md` (if changed).
+- **IMPORTANT**: Both `Cargo.toml` AND `Cargo.lock` must be committed. Missing the lock file will break the deploy.
+- Commit with message: `chore(release): prepare v{VERSION}`
+- Push the branch: `git push -u origin release/v{VERSION}`
+
+## Step 8: Create PR
+
+- Create a PR with `gh pr create` targeting `main`.
+- Title: `chore(release): prepare v{VERSION}`
+- Body should note the version bump and link to the changelog.
+
+## Step 9: Merge PR, tag, and trigger release
+
+After creating the PR, ask the user if they'd like to wait for CI or merge now.
+
+When the user is ready, merge the PR:
+
+```
+gh pr merge --squash --delete-branch
+```
+
+Then checkout main, pull, tag, and push:
+
+```
+git checkout main && git pull
+```
+
+Verify the merged changes are present (the new version should be in `Cargo.toml`). If not, stop and warn the user.
+
+```
+git tag v{VERSION} && git push origin v{VERSION}
+```
+
+## Step 10: Link to pending deployment
+
+After pushing the tag, wait a few seconds, then fetch the workflow run triggered by the tag:
+
+```
+gh run list --workflow=release.yml --limit=1 --json databaseId,status,url
+```
+
+Extract the run URL and print it for the user:
+
+> Tag `v{VERSION}` pushed. Release workflow started.
+>
+> **Approve the deployment here:** {RUN_URL}
+>
+> After approval and deployment:
+> - Confirm the new version on [crates.io](https://crates.io/crates/datafusion-ducklake)
+> - Confirm docs update on [docs.rs](https://docs.rs/datafusion-ducklake) (may take up to a day due to build queue)