refactor(llm-deepseek)!: rename the provider route to deepseek-official

The native adapter's route was named deepseek, colliding with pi-ai's
catalog provider of the same name, so the two DeepSeek paths could never
be mounted side by side. The web settings page needs both configurable at
once. Compositions, fixtures, goldens, scaffolding defaults, and docs all
move together (pre-release, no shim); TUI/session-query-spill/
missing-credential goldens re-recorded through their keyless refresh
modes because provider-name length shifts box padding and spill
truncation points.

packages/examples/acp-demo/tests/load-path.e2e.ts

@@ -42,7 +42,7 @@ const CORDIS_YML = `
 - id: acp-agent
   name: '@deepseek-ai/dsh-acp-demo'
   config:
-    provider: deepseek
+    provider: deepseek-official
     model: deepseek-v4-flash
     persona: 'You are a test agent.'
     workspaceContext: false

packages/examples/tui-demo/README.md

@@ -65,7 +65,7 @@ This package ships no bin. The [`dsh`](../../../apps/cli/README.md) CLI is the t
 - id: tui-agent
   name: '@deepseek-ai/dsh-tui-demo'
   config:
-    provider: deepseek
+    provider: deepseek-official
     model: deepseek-v4-flash
     workspaceContext:
       maxBytes: 65536

packages/examples/tui-demo/README.zh.md

@@ -65,7 +65,7 @@
 - id: tui-agent
   name: '@deepseek-ai/dsh-tui-demo'
   config:
-    provider: deepseek
+    provider: deepseek-official
     model: deepseek-v4-flash
     workspaceContext:
       maxBytes: 65536