threads: order topic chips newest-first beneath General

The gateway already stored a created timestamp per channel/thread but
never sent it over the wire. Now:

- protocol.py: _channel_payload() includes created (unix seconds)
- Protocol.kt: ChannelInfo.created (default 0.0 for legacy gateways)
- ChatScreen: topic switcher sorts threads created-desc (newest right
  after General, swipe new -> old), name as tie-break
- frames.schema.json: document the created field
- ChannelCreatedWireTest: wire deserialization + ordering tests

docs/protocol/frames.schema.json

@@ -97,7 +97,7 @@
   },
   "definitions": {
     "kind": { "type": "string", "enum": ["image", "audio", "video", "document", "voice"] },
-    "channel": { "type": "object", "properties": { "chat_id": {"type":"string"}, "name": {"type":"string"}, "kind": {"type":"string","enum":["default","channel","thread"]}, "parent_chat_id": {"type":["string","null"]}, "is_default": {"type":"boolean"}, "archived": {"type":"boolean"}, "auto": {"type":"boolean","description":"Optional; true on channel.created for a gateway-minted auto-thread."}, "favorite": {"type":"boolean","description":"Optional; cosmetic favorite flag (sorts to the top of the list)."}, "icon": {"type":["string","null"],"description":"Optional; cosmetic icon, a base64-encoded image (PNG/JPEG). Absent/null = auto-generated letter avatar."}, "color": {"type":["string","null"],"description":"Optional; cosmetic avatar color override (#RRGGBB). Absent/null = auto-generated name-hash color."}, "automation": {"type":"boolean","description":"Optional; true when the channel is an automation channel (read-only for the user; only receives gateway-originated output such as cron jobs and webhooks). The app hides the composer and the gateway rejects message.send into it. Never set on the default channel."} } },
+    "channel": { "type": "object", "properties": { "chat_id": {"type":"string"}, "name": {"type":"string"}, "kind": {"type":"string","enum":["default","channel","thread"]}, "parent_chat_id": {"type":["string","null"]}, "is_default": {"type":"boolean"}, "archived": {"type":"boolean"}, "created": {"type":"number","description":"Optional; unix timestamp (seconds) when the channel/thread was created. The app orders threads newest-first in the topic switcher."}, "auto": {"type":"boolean","description":"Optional; true on channel.created for a gateway-minted auto-thread."}, "favorite": {"type":"boolean","description":"Optional; cosmetic favorite flag (sorts to the top of the list)."}, "icon": {"type":["string","null"],"description":"Optional; cosmetic icon, a base64-encoded image (PNG/JPEG). Absent/null = auto-generated letter avatar."}, "color": {"type":["string","null"],"description":"Optional; cosmetic avatar color override (#RRGGBB). Absent/null = auto-generated name-hash color."}, "automation": {"type":"boolean","description":"Optional; true when the channel is an automation channel (read-only for the user; only receives gateway-originated output such as cron jobs and webhooks). The app hides the composer and the gateway rejects message.send into it. Never set on the default channel."} } },
     "media_ref": { "type": "object", "properties": { "media_id": {"type":"string"}, "kind": { "$ref": "#/definitions/kind" }, "mime": {"type":"string"}, "size": {"type":"integer"}, "filename": {"type":"string"}, "message_id": {"type":"string","description":"Optional; set on media.offer to associate the offer with the assistant message it belongs to."} } },
     "runtime": { "type": "object", "description": "Structured runtime-metadata footer (app-controlled display). The gateway ALWAYS sends it on final assistant messages; whether/what is shown is a per-app setting (Settings -> Runtime footer), NOT a hermes config. All keys optional; absent when the data is unavailable (e.g. local models have no cost).", "properties": { "model": {"type":"string","description":"Bare model id, vendor prefix dropped (gpt-5.4)."}, "context_pct": {"type":"integer","description":"Last-call context occupancy, 0-100."}, "cwd": {"type":"string","description":"Home-relative working dir (~)."}, "latency": {"type":"number","description":"Wall-clock turn duration, seconds."}, "cost": {"type":"number","description":"Turn cost, USD."} } }
   },