fix(projman): align command names with git-flow pattern

All projman command names now start with 'projman' prefix to match
git-flow behavior and avoid forced plugin namespace in autocomplete.

Before: /projman:sprint-plan, /projman:project-status
After: /projman sprint plan, /projman project status

This matches git-flow which shows /gitflow commit, /gitflow status.

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

.claude/settings.json

@@ -0,0 +1,3 @@
+{
+  "model": "opusplan"
+}