refactor(release): align with redis-agent-kit (drop GitHub App requirement)

Switch the auto-release workflow to use the built-in github-actions[bot]
identity with GITHUB_TOKEN (and optional RELEASE_PAT fallback for protected
branches), removing the need for a custom GitHub App and its two secrets.

- Drop RELEASE_BOT_APP_ID / RELEASE_BOT_PRIVATE_KEY usage
- Use github-actions[bot] as the release bot
- Token: secrets.RELEASE_PAT || secrets.GITHUB_TOKEN
- Add workflow_dispatch first_release input for bootstrap publishing
- Combine canary build into the release job ("Sanity build (pre-tag)")
- Tolerate missing previous tag for the very first release
- Remove release-drafter-config.yml (not used by this strategy)
- Drop auto:performance label to match redis-agent-kit's 10-label set

Now the only required secret is the existing PYPI token.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

Author: rbs333

.autorc

@@ -1,7 +1,6 @@
 {
   "plugins": [
     "git-tag",
-    "all-contributors",
     "conventional-commits",
     "released"
   ],
@@ -79,14 +78,6 @@
       "color": "#8732bc",
       "overwrite": true
     },
-    {
-      "name": "auto:performance",
-      "changelogTitle": "🏎 Performance",
-      "description": "Improve performance of an existing feature",
-      "releaseType": "patch",
-      "color": "#f4b2d8",
-      "overwrite": true
-    },
     {
       "name": "auto:ci",
       "changelogTitle": "CI/CD Changes",