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

examples/coding-agent/tests/coding-task.e2e.ts

@@ -4,6 +4,7 @@ import { tmpdir } from 'node:os'
 import { join } from 'node:path'
 import { afterEach, describe, expect, it } from 'vitest'
 import type { Context } from 'cordis'
+import { AgentId } from '@deepseek-ai/dsh-agent'
 import { codingHarness, finalText, SYSTEM_PROMPT, waitForIdle } from './harness.ts'
 
 /**
@@ -53,7 +54,7 @@ describe.skipIf(!process.env.DEEPSEEK_API_KEY)('coding task: fix a failing test
     expect(before.status).not.toBe(0)
 
     ctx = await codingHarness(workdir)
-    const agent = ctx.agentLoop.create('e2e-task', {
+    const agent = ctx.agentLoop.create(AgentId('e2e-task'), {
       model: 'deepseek-v4-flash',
       systemPrompt: SYSTEM_PROMPT,
     })

examples/coding-agent/tests/full-loop.e2e.ts

@@ -1,5 +1,6 @@
 import { afterEach, describe, expect, it } from 'vitest'
 import type { Context } from 'cordis'
+import { AgentId } from '@deepseek-ai/dsh-agent'
 import { codingHarness, finalText, SYSTEM_PROMPT, waitForIdle } from './harness.ts'
 
 /**
@@ -20,7 +21,7 @@ afterEach(async () => {
 describe.skipIf(!process.env.DEEPSEEK_API_KEY)('full loop: real model + real bash tool', () => {
   it('runs a bash command on request and reports its output', async () => {
     ctx = await codingHarness(process.cwd())
-    const agent = ctx.agentLoop.create('e2e-loop', {
+    const agent = ctx.agentLoop.create(AgentId('e2e-loop'), {
       model: 'deepseek-v4-flash',
       systemPrompt: SYSTEM_PROMPT,
     })

examples/coding-agent/tests/resume.e2e.ts

@@ -4,6 +4,8 @@ import { join } from 'node:path'
 import { afterEach, describe, expect, it } from 'vitest'
 import type { Context } from 'cordis'
 import type { ReactLoopAgent } from '@deepseek-ai/dsh-agent-loop'
+import { AgentId } from '@deepseek-ai/dsh-agent'
+import { SessionId } from '@deepseek-ai/dsh-session'
 import { codingHarness, finalText, SYSTEM_PROMPT, waitForIdle } from './harness.ts'
 
 /**
@@ -15,7 +17,7 @@ import { codingHarness, finalText, SYSTEM_PROMPT, waitForIdle } from './harness.
  */
 
 const SECRET = 'plum-galaxy-1791'
-const SESSION_ID = 'resume-e2e-session'
+const SESSION_ID = SessionId('resume-e2e-session')
 
 let ctx: Context | undefined
 let root: string | undefined
@@ -38,7 +40,7 @@ describe.skipIf(!process.env.DEEPSEEK_API_KEY)('resume: continue a persisted ses
     // log on disk survives.
     ctx = await codingHarness(process.cwd(), root)
     const first = ctx.agents.create({
-      agentId: 'resume-1',
+      agentId: AgentId('resume-1'),
       sessionId: SESSION_ID,
       agentOptions: { model: 'deepseek-v4-flash', systemPrompt: SYSTEM_PROMPT },
     }).agent as ReactLoopAgent
@@ -52,7 +54,7 @@ describe.skipIf(!process.env.DEEPSEEK_API_KEY)('resume: continue a persisted ses
     // run 1's exchange as conversation history.
     ctx = await codingHarness(process.cwd(), root)
     const resumed = (await ctx.agents.resume({
-      agentId: 'resume-2',
+      agentId: AgentId('resume-2'),
       resumeSessionId: SESSION_ID,
       agentOptions: { model: 'deepseek-v4-flash', systemPrompt: SYSTEM_PROMPT },
     })).agent as ReactLoopAgent