docs: tier the tree by lifetime, so staleness shows in the path (V-446)

Seventeen markdown files at the repo root, twelve of them dated one-shot
reports sitting next to CLAUDE.md. That is why stale docs read as
current: nothing in the path said which was which.

Root now keeps CLAUDE.md and AGENTS.md. Living docs move under docs/
and carry a Last verified line. Dated measurements move to docs/evals/
ISO-prefixed, and are never edited after the day, so a newer number is
a new file. The senior review moves to docs/archive/.

Every reference was rewritten across markdown, Go comments, the Makefile
and the recall fixture. The touched Go packages still build.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

docs/plans/2026-07-10-router-lfm-foundation.md

@@ -6,7 +6,7 @@
 > use the embedded LFM model paths or old single-object examples as current ops
 > guidance; see `2026-07-18-qwen3-resident-training-eval.md`.
 
-> Scope from `REARCH.md`. Make Maven trustworthy: the LFM becomes the router
+> Scope from `docs/rearchitecture.md`. Make Maven trustworthy: the LFM becomes the router
 > (fixes "messes up queries" / "doesn't take notes"), the engine actually runs
 > (fixes stub replies), dates stop being read as "number dot number dot number",
 > and telegram becomes a reach channel. NOT in scope: on-demand 4B reasoner,
@@ -693,7 +693,7 @@ ssh kami@192.168.1.104 'curl -s localhost:9201/api/chat -d "{\"text\":\"запо
 4. `docker compose up -d mavend && docker logs -f maven-mavend-1` — confirm the
    phraser spawns and no `phraser: NewStub` path. Run the two verify curls.
 5. Update `AGENTS.md`: LFM model download + note that routing is now LFM-first
-   with classifier fallback (`REARCH.md` is the design of record).
+   with classifier fallback (`docs/rearchitecture.md` is the design of record).
 
 ---