[grade=B urn:ump:mao7vadnesmquhmgr4oeg554edt6fn3ykxyiydtfs2psoekd4s7q] P7 tailscale provider: wire coord client via ctx delegation

Dogfood finding #2: createTailscaleProvider() built with coordClient=null;
nothing in prod ever called attachCoordClient() (the wiring the provider
docblock promised never landed), so wizard credential validation always
failed not_configured even with a valid stored token. Pass a delegating
proxy that fetches a fresh coord client per call via the sanctioned
ctx.tailscaleCoord.getClient pattern (token re-read from credentialManager
each call). Full suite 3413/3413.

dashcaddy-api/src/app.js

@@ -779,7 +779,29 @@ async function createApp() {
   // Private Network wizard (DC-152). Dogfood finding 2026-10-04: the wizard
   // factory needs INSTANCES keyed by mode id; without them every mode
   // selection 503s provider_unavailable (unit tests inject their own map).
-  const p7TailscaleProvider = require('./network/providers/tailscale').createTailscaleProvider(); // eslint-disable-line global-require
+  // Coord client wiring (dogfood finding #2, 2026-10-04): the provider is
+  // built with coordClient=null and nothing ever called attachCoordClient()
+  // in prod (the promised routes/network.js wiring never landed), so wizard
+  // credential validation always failed not_configured. Delegate every coord
+  // method to a FRESH client per call — the sanctioned context pattern
+  // (ctx.tailscaleCoord.getClient re-reads the token from credentialManager
+  // each call, so wizard-stored tokens take effect without a restart).
+  const p7CoordProxy = new Proxy({}, {
+    get(_t, prop) {
+      if (typeof prop !== 'string') return undefined;
+      return async (...args) => {
+        const client = await ctx.tailscaleCoord.getClient();
+        const fn = client ? client[prop] : null;
+        if (typeof fn !== 'function') {
+          throw new Error('coord client method unavailable: ' + String(prop));
+        }
+        return fn.apply(client, args);
+      };
+    },
+  });
+  const p7TailscaleProvider = require('./network/providers/tailscale').createTailscaleProvider({ // eslint-disable-line global-require
+    coordClient: p7CoordProxy,
+  });
   const p7WireGuardProvider = require('./network/providers/wireguard').createWireGuardProvider(); // eslint-disable-line global-require
   apiRouter.use('/network/wizard', networkWizardRoutes({
     registry: { getActiveProvider },