Add supervisor process manager UI

[kvinwang]

Summary

• Add a supervisor process manager page accessible from the top-right hamburger menu
• Shows all supervisor processes with name, ID, status, PID, and action buttons (Stop/Remove)
• Auto-refreshes every 3 seconds while the overlay is open
• "Clear Stopped" button removes only non-running processes (not a blanket clear)
• Backend uses proper pRPC methods (SvList/SvStop/SvRemove) so the API appears in the auto-generated OpenAPI schema

Changed files

• vmm/rpc/proto/vmm_rpc.proto — Add SvList, SvStop, SvRemove RPC methods and SvProcessInfo message
• vmm/src/main_service.rs — Implement the three supervisor RPC methods
• vmm/src/main_routes.rs — Remove hand-crafted REST supervisor routes
• vmm/ui/src/templates/app.html — Add menu item and process manager overlay
• vmm/ui/src/composables/useVmManager.ts — Add process manager logic using pRPC
• vmm/ui/src/styles/main.css — Add process manager styles
• vmm/src/console_v1.html — Rebuilt UI artifact

Depends on

• Remove passt networking mode support #495 (Remove passt networking mode support)

Test plan

• cargo fmt and cargo clippy pass
• UI builds successfully
• Open process manager from menu, verify processes are listed
• Stop a running process, verify status updates after refresh
• Remove a stopped process, verify it disappears
• "Clear Stopped" removes only non-running processes