Declare the AI owner, and let every node borrow its model over the mesh

vv_is_ai_host() was `=== 'host1'`, which made a physical fact — that is where the
GPU is — look like a rule. AI_OWNER_HOST declares it, so the card can move to a
rebuilt host3 or a friend's spare.

The gate was also doing two jobs. Assistant docks and findings strips now ask
whether a model is reachable, so a node without a GPU gets them by borrowing;
the AI tab asks whether this is the owner, because that page carries the bug
reports, the index and the model configuration — the surface where the
vocabulary assumes you built the mesh.

Resolution is local, then owner, then anyone else declaring a model, pinned once
it answers. Pinned rather than re-derived per call: a mesh that re-decides every
request eventually decides differently mid-conversation, and a chat whose second
turn lands on another machine has no history there. Cleared only on a transport
failure, and only when there is somewhere else to go — a single-node mesh whose
model is down should say so, not report AI as unconfigured.

Plugin/unraid/Varaverk.page

@@ -221,7 +221,10 @@ $validTabs = ['monitor', 'scheduler', 'docker', 'watchdog', 'partnership', 'fall
 // include/ai.php only ever reads the *local* {HOST}_OLLAMA_URL — there is no Tailscale resolver
 // in the PHP layer the way there is in the shell. On any other host the tab could only render
 // and then fail its own health check.
-$_vv_ai = vv_ai_ui_on();
+// The tab is the owner-only surface — it carries the bug reports, the index and the model
+// configuration. Assistant docks elsewhere use vv_ai_ui_on(), which every node with a reachable
+// model passes.
+$_vv_ai = vv_ai_owner_ui_on();
 if ($_vv_ai) $validTabs[] = 'ai';
 
 if (!in_array($tab, $validTabs)) $tab = 'monitor';