Unexport internal-only gating types to hold the knip ratchet

Why: BuildWorkspaceOptions / RdmErrorKind / RdmErrorView are only consumed
inside their own modules, so exporting them pushed unused exports 45 over
the knip baseline 43 and failed make test.

Evidence: npx vitest run 23 files / 112 tests pass; node scripts/check-knip.mjs
passes at 42 <= 43.

Impact: no API change - consumers pass object literals and consume the
classified error structurally.

Refs: 2026-10-12 diagnostic report, increment 2.

src/rdmErrors.ts

@@ -5,9 +5,9 @@
 // 400 + "unknown or disabled command"（cmdbus.go Dispatch），总线未挂载回
 // 503 "commands disabled"（server.go execCommand）。
 
-export type RdmErrorKind = 'capability' | 'auth' | 'query'
+type RdmErrorKind = 'capability' | 'auth' | 'query'
 
-export interface RdmErrorView {
+interface RdmErrorView {
   kind: RdmErrorKind
   message: string
   raw: string

src/workspaces.ts

@@ -49,7 +49,7 @@ function shortcutNum(raw?: string): number | null {
   return n >= 1 && n <= 9 ? n : null
 }
 
-export interface BuildWorkspaceOptions {
+interface BuildWorkspaceOptions {
   /** rdm.inspect.* 命令面探测通过（store.rdmAuditAvailable）。默认 false：能力未知/缺失不展示审计入口。 */
   rdmAudit?: boolean
 }