feat: configure context7-mcp and proxmox-mcp as stdio servers

- Set context7-mcp restart: "no" for on-demand execution
- Add context7-mcp to crush.json mcp configuration
- Fix proxmox-mcp Dockerfile to use python module directly
- Update proxmox-mcp entrypoint to "python -m proxmox_mcp.server"
- Add git dependency for proxmox-mcp git+ dependencies
- Remove --frozen flag (no lock file available)

crush.json

@@ -5,6 +5,10 @@
       "command": "docker",
       "args": ["run", "-i", "--rm", "kneldevstack-aimiddleware-bash-language-server", "start"]
     },
+    "context7": {
+      "command": "docker",
+      "args": ["run", "-i", "--rm", "kneldevstack-aimiddleware-context7-mcp"]
+    },
     "docker": {
       "command": "docker",
       "args": ["run", "-i", "--rm", "kneldevstack-aimiddleware-docker-language-server", "start", "--stdio"]