release: v5.3.0 - Sprint 6 Visual Branding Overhaul

Sprint 6 adds consistent visual headers across all 12 plugins:
- Projman: Double-line headers with phase indicators
- Other plugins: Single-line headers with plugin icons
- 109 files updated (23 agents + 86 commands)
- 4 Wiki branding specification pages

Also fixes documentation drift:
- Version sync across CLAUDE.md, marketplace.json, README.md
- Added 18 missing commands to documentation

Closes Sprint 6 milestone.

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

.claude-plugin/marketplace.json

@@ -6,7 +6,7 @@
   },
   "metadata": {
     "description": "Project management plugins with Gitea and NetBox integrations",
-    "version": "5.2.0"
+    "version": "5.3.0"
   },
   "plugins": [
     {