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-assembled-assistant-messages-only.md

@@ -19,7 +19,7 @@ ACP `session/load` can replay prior assistant messages as complete content block
 ## Acceptance criteria
 
 - `SessionEventMap` drops `assistant/chunk`, or marks it as non-persisted if a transitional live event is needed.
-- [Session persistence docs](../../../../packages/session-persistence/session-persistence/README.md) no longer require every stream chunk to be stored verbatim.
+- [Session persistence docs](../../../../packages/session/session-persistence/README.md) no longer require every stream chunk to be stored verbatim.
 - `llm-replay` and ACP snapshots use an explicit replay fixture format or sidecar for model chunks.
 - `session/load` renders completed assistant messages from `assistant/message`.
 - Stored logs get much smaller and remain `seq`-contiguous without chunk holes.