feat(types): brand bash ids + stop brand erosion; extract Branded to dsh-brand

Type-only change (brands are zero-cost casts; no runtime/wire impact). Closes
the two gaps in the "brand ids that cross package boundaries" policy and fixes
the dependency direction so a capability package never pulls in an unrelated one.

- Extract the `Branded<B>` primitive into a new standalone type-only package
  `@deepseek-ai/dsh-brand` (packages/util/brand) with no harness-package deps.
  dsh-llm keeps its owned CallId but imports Branded from dsh-brand; dsh-session,
  dsh-agent, and dsh-bash all import Branded from there. dsh-bash depends on
  dsh-brand ALONE — never on dsh-llm or dsh-session (the architectural fix: a
  generic execution backend must not couple to the LLM or session vocabulary).
- Mint BashTaskId + OwnerToken in dsh-bash and thread them through BashTask.id,
  the get/ownerOf/list/readOutput/kill seam, the bash-local generation site, and
  the dsh-tool-bash validate/access surface. OwnerToken is a DISTINCT brand from
  SessionId so the seam stays decoupled; dsh-tool-bash is the single boundary
  that casts SessionId -> OwnerToken.
- Brand at the SOURCE, not via mid-pipeline casts: agent-loop's Config types
  agents[].id as AgentId and resumeSessionId as SessionId, so the brand enters
  at the config boundary and the inner create()/resume casts disappear (only the
  genuinely-new per-run session-id string is cast).
- Stop brand erosion: propagate CallId/SessionId/AgentId to the registry/store
  Map keys and public params/exports (SessionStore, AgentRegistry + factory
  options, the ACP session-id surface + ToolPresenter CallId map, the
  persistence coordinator, invariants pendingCalls, the pi-ai tool-call maps).
- Docs: document BashTaskId/OwnerToken in bash.md (type-equiv re-pasted), point
  the Branded type-equiv at dsh-brand, fix stale param types in the session/
  agent/bash READMEs, regenerate the cordis catalog + module graph.

Implements docs/rfc/proposed/architecture/2026-06-20-branded-ids.md

packages/support/ui-stdio/src/index.ts

@@ -22,7 +22,7 @@ import { createInterface } from 'node:readline'
 import type { Readable, Writable } from 'node:stream'
 import type { Context } from 'cordis'
 import z from 'schemastery'
-import type {} from '@deepseek-ai/dsh-agent'
+import { AgentId } from '@deepseek-ai/dsh-agent'
 
 export const name = 'ui-stdio'
 export const inject = ['agents']
@@ -69,7 +69,7 @@ export function createStdioChat(ctx: Context, config: Config, runtime: StdioRunt
   // Loader validation, so it must be self-contained rather than trusting the
   // cast — `config.welcome as string` would otherwise be `undefined` on `{}`.
   const welcome = config.welcome ?? 'ready.'
-  const agentId = config.agent ?? 'main'
+  const agentId = AgentId(config.agent ?? 'main')
   const { input, output, exit } = runtime
 
   let inReasoning = false