feat(app): interactive system map (/map)

A spatial control surface for the whole node. Tools, jobs, services, and
frontends sit in lanes with program-source grips; edges show requires
(dependency), same-program siblings, and exposure to LAN/Internet targets.

Direct manipulation, each backed by the existing config PUT + apply:
- drag a node to LAN/Internet to set reach (internal/public)
- delete an exposure line or a node (with confirm) to unexpose/remove
- right-click or the per-node ⋯ menu: open, restart, expose, delete
- click the source grip to open the backing program

Nodes are draggable with Shift-/toggle box-select; layout persists to
localStorage with a reset control. Adds useSetReach/useDeleteDeployment
hooks, the @xyflow/react dep, and the nav entry + route.

app/package.json

@@ -15,6 +15,7 @@
     "@tanstack/react-query": "^5.90.21",
     "@xterm/addon-fit": "^0.11.0",
     "@xterm/xterm": "^6.0.0",
+    "@xyflow/react": "^12.11.1",
     "class-variance-authority": "^0.7.1",
     "clsx": "^2.1.1",
     "lucide-react": "^0.575.0",