fix(plugins): sync plugin.json versions with marketplace.json

Plugin load failures were caused by version mismatch between
marketplace.json and individual plugin.json files:
- contract-validator: 1.2.0 vs 1.1.0
- git-flow: 1.2.0 vs 1.0.0
- projman: 3.4.0 vs 3.3.0
- clarity-assist: 1.2.0 vs 1.0.0
- doc-guardian: 1.1.0 vs 1.0.0

Claude Code silently fails to load plugins when versions don't match.

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

plugins/git-flow/.claude-plugin/plugin.json

@@ -1,6 +1,6 @@
 {
   "name": "git-flow",
-  "version": "1.0.0",
+  "version": "1.2.0",
   "description": "Git workflow automation with intelligent commit messages and branch management",
   "author": {
     "name": "Leo Miranda",