manifest(smart_panel): vendor as domain (deeplethe.com)

The `vendor` field is a domain-style identifier — the lamp manifest
uses `example.dev`. smart_panel had a bare `deeplethe`; aligned it to
the domain form for consistency.

Committed directly to dev per the branching convention (dev accepts
maintainer direct pushes; main stays PR-only).

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

Author: WaylandYang

examples/smart_panel_manifest.yaml

@@ -15,7 +15,7 @@ dcp: 0.3
 device:
   id:     smart-panel-01
   model:  lilygo_t_panel_s3_h720
-  vendor: deeplethe
+  vendor: deeplethe.com
 
 intents:
   # ─── v0.3 — visual + audio (no CAN needed) ───────────────────────