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.

.agents/notes/rejected/simplification/2026-06-20-fold-session-persistence-interface.md

@@ -22,7 +22,7 @@ The implementing PR should update the [capability seams](../../implemented/archi
 - `dsh-session` exports the persistence service type, coordinator, and contract helpers.
 - JSONL and SQLite backend packages depend on `dsh-session` directly.
 - `agent-loop` resume uses the session-owned service key.
-- [Session persistence](../../implemented/architecture/2026-06-14-session-persistence.md), [shared persistence write coordinator](../../implemented/architecture/2026-06-18-shared-persistence-write-coordinator.md), and [package docs](../../../../packages/session-persistence/session-persistence/README.md) explain why backend implementations remain separate.
+- [Session persistence](../../implemented/architecture/2026-06-14-session-persistence.md), [shared persistence write coordinator](../../implemented/architecture/2026-06-18-shared-persistence-write-coordinator.md), and [package docs](../../../../packages/session/session-persistence/README.md) explain why backend implementations remain separate.
 
 ## What we give up