chore: remove obsolete docs/references/ planning documents

Deleted (obsolete planning docs from pre-implementation phase):
- docs/references/MCP-GITEA.md - wrong MCP server location
- docs/references/MCP-WIKIJS.md - Wiki.js MCP never implemented
- docs/references/PLUGIN-PMO.md - projman-pmo not yet built
- docs/references/PLUGIN-PROJMAN.md - superseded by plugins/projman/README.md
- docs/references/PROJECT-SUMMARY.md - outdated architecture

Updated references in:
- CLAUDE.md - removed docs/references/ from documentation index
- docs/CANONICAL-PATHS.md - removed references directory from structure
- docs/UPDATING.md - updated to reference current documentation
- plugins/projman/mcp-servers/gitea/README.md - fixed related docs links
- plugins/projman/mcp-servers/gitea/TESTING.md - fixed resource links

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

CLAUDE.md

@@ -177,7 +177,7 @@ Stored in Gitea Wiki under `lessons-learned/sprints/`.
 | Document | Purpose |
 |----------|---------|
 | `docs/CANONICAL-PATHS.md` | **Single source of truth** for paths |
-| `docs/references/` | Reference specs and summaries |
+| `docs/UPDATING.md` | Update guide for the marketplace |
 | `plugins/projman/CONFIGURATION.md` | Projman setup guide |
 | `plugins/projman/README.md` | Projman full documentation |