refactor: brand the command lifecycle pairing id as CommandId

commandId crosses three boundaries (session log, wire admission response,
client flow pairing), so per the branded-id rule it becomes
Branded<'CommandId'>, declared in a new pure @deepseek-ai/dsh-commands/brand
outlet (the dsh-llm/brand shape: type + constructor, no Context merges, so
wire and client programs can name it without loading the host plugin). The
event payloads, CommandExecution, and the executor mint carry the brand; the
wire schema gains commandIdSchema as the domain's single brand-cast point
(the approvals precedent); CommandNode and the fixture's fabrication cast
follow type-only.

packages/ui/commands/tsconfig.json

@@ -23,6 +23,9 @@
     {
       "path": "../../core/session"
     },
+    {
+      "path": "../../util/brand"
+    },
     {
       "path": "../../support/invariants"
     }