chore: remove /release skill, superseded by release workflows (#126)

* chore: remove /release skill, superseded by release workflows

publish.yml now publishes to pub.dev and creates the GitHub release after
the release PR merges (#122); running the skill would race the pipeline.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

* chore: drop 'Step 1' from prepare-release skill title

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

---------

Co-authored-by: Claude Opus 5.5 <noreply@anthropic.com>

Author: muzahidul-opti

.claude/skills/prepare-release/SKILL.md

@@ -4,9 +4,9 @@ description: Prepare release branch with version updates and create PR for Optim
 compatibility: Requires Flutter SDK project
 ---
 
-# Prepare Release - Step 1 of Release Workflow
+# Prepare Release
 
-Creates prep branch, updates versions, fetches PR summaries, and creates PR.
+Creates prep branch, updates versions, fetches PR summaries, and creates PR. After the PR merges, `release.yml` and `publish.yml` tag, publish to pub.dev, and create the GitHub release.
 
 ## Usage