refactor: consolidate plugins into plugins/ directory

- Created plugins/ directory to centralize all plugins
- Moved projman and project-hygiene into plugins/
- Updated .mcp.json paths from ../mcp-servers/ to ../../mcp-servers/
- Updated CLAUDE.md governance section with new directory structure
- Updated README.md with new repository structure diagram
- Fixed all path references in documentation

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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

plugins/projman/.mcp.json

@@ -0,0 +1,14 @@
+{
+  "mcpServers": {
+    "gitea": {
+      "command": "${CLAUDE_PLUGIN_ROOT}/../../mcp-servers/gitea/.venv/bin/python",
+      "args": ["-m", "mcp_server.server"],
+      "cwd": "${CLAUDE_PLUGIN_ROOT}/../../mcp-servers/gitea"
+    },
+    "wikijs": {
+      "command": "${CLAUDE_PLUGIN_ROOT}/../../mcp-servers/wikijs/.venv/bin/python",
+      "args": ["-m", "mcp_server.server"],
+      "cwd": "${CLAUDE_PLUGIN_ROOT}/../../mcp-servers/wikijs"
+    }
+  }
+}