fix(voice): refuse unrequested Gemini tool calls and share pointer turns

in push-to-talk, answer a Gemini tool call that arrives with no input, reply
or tool result outstanding with a failure instead of running it, and refuse
every other call in the reply it starts, including one after unprompted
speech; the reply stays tracked so the next input retires it and its late
boundary cannot close the user's turn

in push-to-talk, a caption that arrives after its turn ended no longer opens
a reply, so the next request is not retired with its tool calls discarded
open mic cannot tell either case from a new reply and stays unchanged

check packet ownership after the narration callback before queuing tools,
and raise the per-connection call history to 4096 IDs

move the pointer turn event, context item and announcement into
pointerContext so the OpenAI and Gemini controllers share them, and drop the
Gemini token route's copy of the shared exact-Origin comparison

server/providers/gemini/request.js

@@ -17,6 +17,7 @@ export function isGeminiRequestOriginAllowed(
     typeof host !== 'string' ||
     typeof origin !== 'string' ||
     !host ||
+    !origin ||
     /[\s/?#@\\]/.test(host)
   )
     return false;
@@ -31,29 +32,14 @@ export function isGeminiRequestOriginAllowed(
     }).ok
   )
     return false;
+  // The shared gate compares a present Origin exactly with this authority;
+  // this route also requires the Origin and an allowed Host.
   const boundHost = String(configuredHost || '')
     .trim()
     .toLowerCase();
-  if (
-    !isAllowedHost(host, resolveAllowedHosts(configuredAllowedHosts), [
-      boundHost,
-    ])
-  )
-    return false;
-  try {
-    const authority = new URL(`${protocol}//${host}`);
-    const source = new URL(origin);
-    return (
-      source.origin === authority.origin &&
-      source.username === '' &&
-      source.password === '' &&
-      source.pathname === '/' &&
-      source.search === '' &&
-      source.hash === ''
-    );
-  } catch {
-    return false;
-  }
+  return isAllowedHost(host, resolveAllowedHosts(configuredAllowedHosts), [
+    boundHost,
+  ]);
 }
 
 /** Admit only the existing input gesture; callers cannot supply model/setup. */