feat: add template artifact job to prepare-release pipeline

- Add --version, --tarball-dir, and --output-dir flags to
  prepare-template-artifact.ts for reuse across CI and release
- Add template-artifact job to prepare-release workflow that downloads
  release tarballs and produces a template zip artifact
- Update install-appkit-tarball skill with --template mode for
  scaffolding new apps from CI template artifacts
- Temporarily trigger prepare-release on this branch for testing

Signed-off-by: Pawel Kosiec <pawel.kosiec@databricks.com>

Author: pkosiec

.claude/skills/install-appkit-artifact.md

@@ -0,0 +1,194 @@
+---
+name: install-appkit-artifact
+description: "Install appkit CI artifacts into a project or scaffold a new app from a CI template artifact. Downloads from the prepare-release CI workflow (default) or builds locally. Use when testing appkit release candidates, installing pre-release appkit, scaffolding a new app from template, or when user says 'install appkit tarball', 'install appkit artifact', 'install local appkit', 'use local appkit', 'link appkit tgz', 'install appkit from CI', 'create app from template', 'init app from CI'."
+user-invocable: true
+allowed-tools: Read, Edit, Bash, Glob
+---
+
+# Install AppKit Tarball
+
+Installs AppKit tgz packages into a project from either the CI prepare-release workflow or a local build. Can also scaffold a new app from a CI template artifact.
+
+## Arguments
+
+Parse the user's input to determine mode and options:
+
+- **No args** → CI mode, latest successful prepare-release run, install in CWD
+- **GitHub Actions URL** (contains `actions/runs/`) → CI mode, extract run ID from URL
+- **Numeric run ID** → CI mode, that specific run
+- **`--local <path>`** → Local build mode from the given appkit repo path
+- **`--dir <path>`** (combinable with any above) → Override install target directory (default: CWD)
+- **`--template`** → Template mode: scaffold a new app from the CI template artifact instead of installing tarballs into an existing project
+
+## Workflow
+
+Follow these steps exactly:
+
+### Step 1: Determine mode
+
+If `--template` was provided, go to **Template Mode** below. Otherwise continue with **Install Mode**.
+
+---
+
+## Install Mode
+
+### Step 2: Determine target directory
+
+If `--dir` was provided, use that path. Otherwise use the current working directory.
+Verify `package.json` exists in the target directory.
+
+### Step 3: Get tgz files
+
+#### Option A: CI mode (default)
+
+**3a. Find the workflow run:**
+
+If no run ID was provided, get the latest successful run:
+
+```bash
+gh run list --repo databricks/appkit --workflow prepare-release.yml --status success --limit 1 --json databaseId,number
+```
+
+If a GitHub Actions URL was provided, extract the run ID from it (the number after `/runs/`).
+
+**3b. Find the artifact name:**
+
+```bash
+gh api "repos/databricks/appkit/actions/runs/{RUN_ID}/artifacts" --jq '.artifacts[] | select(.name | test("^appkit-release-[0-9]")) | .name'
+```
+
+**3c. Download the artifact:**
+
+```bash
+gh run download {RUN_ID} --repo databricks/appkit --name "{ARTIFACT_NAME}" --dir /tmp/appkit-release-artifacts
+```
+
+**3d. Verify checksums:**
+
+```bash
+cd /tmp/appkit-release-artifacts && shasum -a 256 -c SHA256SUMS
+```
+
+Note: Use `shasum -a 256` (macOS) not `sha256sum` (Linux).
+
+**3e. Print the downloaded version:**
+
+```bash
+cat /tmp/appkit-release-artifacts/VERSION
+```
+
+The tgz files are now at `/tmp/appkit-release-artifacts/databricks-appkit-*.tgz` and `/tmp/appkit-release-artifacts/databricks-appkit-ui-*.tgz`.
+
+#### Option B: Local build mode
+
+**3a. Build tgz files:**
+
+```bash
+cd {LOCAL_APPKIT_PATH} && pnpm pack:sdk
+```
+
+**3b. Find the tgz files:**
+
+Glob for `*.tgz` in:
+- `{LOCAL_APPKIT_PATH}/packages/appkit/tmp/*.tgz`
+- `{LOCAL_APPKIT_PATH}/packages/appkit-ui/tmp/*.tgz`
+
+There should be exactly one tgz in each directory.
+
+### Step 4: Copy tgz files to target directory
+
+Copy both `databricks-appkit-*.tgz` and `databricks-appkit-ui-*.tgz` to the target directory.
+
+### Step 5: Update package.json
+
+Read `package.json` in the target directory. Edit `@databricks/appkit` and `@databricks/appkit-ui` dependency values to use `file:./` prefix pointing to the tgz filenames.
+
+For example, if the tgz file is `databricks-appkit-0.22.0.tgz`:
+```json
+"@databricks/appkit": "file:./databricks-appkit-0.22.0.tgz"
+```
+
+Same pattern for `@databricks/appkit-ui`.
+
+### Step 6: Install dependencies
+
+Run in the target directory:
+
+```bash
+npm install --force ./databricks-appkit-{VERSION}.tgz ./databricks-appkit-ui-{VERSION}.tgz
+```
+
+### Step 7: Clean up
+
+If CI mode was used, remove the temp directory:
+
+```bash
+rm -rf /tmp/appkit-release-artifacts
+```
+
+### Step 8: Report
+
+Print a summary:
+- Source: CI run #{number} or local build from {path}
+- Version installed
+- Target directory
+- Installed packages
+
+---
+
+## Template Mode
+
+Scaffolds a new app by downloading the template artifact from a CI run and using `databricks apps init`.
+
+### Step 2: Find the workflow run
+
+If no run ID was provided, get the latest successful run:
+
+```bash
+gh run list --repo databricks/appkit --workflow prepare-release.yml --status success --limit 1 --json databaseId,number
+```
+
+If a GitHub Actions URL or numeric run ID was provided, use that instead.
+
+### Step 3: Find the template artifact name
+
+```bash
+gh api "repos/databricks/appkit/actions/runs/{RUN_ID}/artifacts" --jq '.artifacts[] | select(.name | test("^appkit-template-")) | .name'
+```
+
+### Step 4: Download the template artifact
+
+```bash
+gh run download {RUN_ID} --repo databricks/appkit --name "{ARTIFACT_NAME}" --dir /tmp/appkit-template-artifact
+```
+
+### Step 5: Unzip the template
+
+```bash
+mkdir -p /tmp/appkit-template && unzip -o /tmp/appkit-template-artifact/template.zip -d /tmp/appkit-template
+```
+
+Note: The zip is named `template.zip` for release artifacts and `pr-template.zip` for PR artifacts. Check which file exists.
+
+### Step 6: Scaffold the app
+
+Run `databricks apps init` with the `--template` flag pointing to the unzipped directory:
+
+```bash
+databricks apps init --template /tmp/appkit-template
+```
+
+If `--dir` was provided, also pass it as the output location. The user may also want to pass additional flags — ask if needed.
+
+### Step 7: Clean up
+
+```bash
+rm -rf /tmp/appkit-template-artifact /tmp/appkit-template
+```
+
+### Step 8: Report
+
+Print a summary:
+- Source: CI run #{number}
+- Template directory used
+- App created at target path

.claude/skills/install-appkit-tarball.md

@@ -162,7 +162,7 @@ jobs:
         run: pnpm pack:sdk
 
       - name: Prepare template artifact
-        run: pnpm exec tsx tools/prepare-template-artifact.ts "${{ steps.version.outputs.version }}"
+        run: pnpm exec tsx tools/prepare-template-artifact.ts --version "${{ steps.version.outputs.version }}"
 
       - name: Install template dependencies
         working-directory: pr-template