refactor(session): fold the session family into packages/session/

git mv the 12 packages from session-persistence/, session-projection/,
session-title/, and telemetry/ into one session/ group per the
regrouping RFC; merge the four group READMEs into one bilingual
triplet; rewrite the group segment in tsconfig references (intra-group
references shorten to ../<pkg>), tsconfig.base.json paths/globs,
knip.json keys, vitest include, gate scripts, and authored doc/note
citations; regenerate module graph, doc graphs, catalogs, and the
lockfile importer keys. No npm names change.

Full unit suite: 8779 passed; the 18 reported failures reproduce as
env flakes (ambient-proxy IPv6 tunneling, watched-dir inotify
timeouts under parallel load) — each passes in isolation with
NO_PROXY set, matching their known pre-existing behavior on master.

packages/session/session-title-first-message-llm/tests/provider.e2e.ts

@@ -0,0 +1,59 @@
+import { createUserMessage } from '@deepseek-ai/dsh-llm'
+import { afterEach, describe, expect, it } from 'vitest'
+import { Context } from 'cordis'
+import LlmService from '@deepseek-ai/dsh-llm'
+import * as LlmDeepSeek from '@deepseek-ai/dsh-llm-deepseek'
+import SessionStore, { SessionId } from '@deepseek-ai/dsh-session'
+import SessionTitleService from '@deepseek-ai/dsh-session-title'
+import * as FirstMessageTitleProvider from '@deepseek-ai/dsh-session-title-first-message-llm'
+
+const contexts: Context[] = []
+
+afterEach(async () => {
+  await Promise.all(contexts.splice(0).map(ctx => ctx.fiber.dispose()))
+})
+
+describe.skipIf(!process.env.DEEPSEEK_API_KEY)('first-message title provider with real DeepSeek API', () => {
+  it('replaces the fallback with a short model title', async () => {
+    const ctx = new Context()
+    contexts.push(ctx)
+    await ctx.plugin(LlmService)
+    await ctx.plugin(LlmDeepSeek, { thinking: 'disabled' })
+    await ctx.plugin(SessionStore)
+    await ctx.plugin(SessionTitleService, {
+      fallbackMaxWords: 5,
+      fallbackMaxBytes: 40,
+      maxTitleBytes: 80,
+    })
+    await ctx.plugin(FirstMessageTitleProvider, {
+      targetWords: 5,
+      targetCjkCharacters: 10,
+      maxInputBytes: 4_096,
+      maxOutputTokens: 64,
+      timeoutMs: 60_000,
+      provider: 'deepseek-official',
+      model: 'deepseek-v4-flash',
+    })
+    const session = ctx.sessions.create(SessionId('real-title-provider'))
+    session.append('turn/start', {
+      turn: 1,
+    })
+    const message = session.append('user/message', createUserMessage({
+      content: [{ type: 'text', text: 'Explain why append-only logs make session titles durable.' }],
+      source: { kind: 'user' },
+    }), { surfaceOp: 'append' })
+
+    const title = await ctx.sessionTitle.refresh(session)
+
+    expect(title).toMatchObject({
+      messageSeqs: [message.seq],
+      source: {
+        kind: 'provider',
+        provider: 'session-title-first-message-llm',
+        model: { provider: 'deepseek-official', model: 'deepseek-v4-flash' },
+      },
+    })
+    expect(title?.title.length).toBeGreaterThan(0)
+    expect(Buffer.byteLength(title?.title ?? '', 'utf8')).toBeLessThanOrEqual(80)
+  })
+})