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>

PROGRESS.md

@@ -74,7 +74,7 @@ full-weight checkpoint at step 1000/8077; evaluation and Qwen3 SFT tooling are
 tracked in `docs/plans/2026-07-18-qwen3-resident-training-eval.md`.
 
 Consolidated status. The reactive↔proactive core is closed and testable through
-the web PWA. The former SPEC's open items 1–7 (now `DESIGN.md` § execution ledger) are landed (protocol doc, away-channel
+the web PWA. The former SPEC's open items 1–7 (now `docs/design.md` § execution ledger) are landed (protocol doc, away-channel
 fallthrough, CalDAV poller, quiet-hours schedule, tools enable/disable, note RAG,
 passkey step-up); item 8 (multi-user) is deliberately deferred — see the tail.
 The two big infra gaps from the jul5 revision are closed on `overnight-jul5`:
@@ -145,7 +145,7 @@ tests, `-race` in `make test`.
   time window (`voice.quiet_hours`, HH:MM, midnight-crossing handled) now sets it
   on each tick — in addition to the "тихий режим" voice toggle. Both activate quiet.
 - **Client protocol (SPEC item 1):** the voice wire format (length-prefixed JSON
-  frames) is published in `PROTOCOL.md`, generated from `internal/voice/wire.go`
+  frames) is published in `docs/protocol.md`, generated from `internal/voice/wire.go`
   so third-party clients don't need the Go source.
 - **Passkey step-up (SPEC item 7):** `internal/webauthn` does real WebAuthn —
   ES256/P-256 register + assert, ecdsa signature verification, rpIdHash + UP/UV
@@ -463,6 +463,6 @@ Not neglect — the one item where doing nothing now beats doing something:
 - **The hard part is speaker attribution, and it needs the second voice.** A
   voice-print discriminator (kami vs gf vs unknown) can't be trained or tuned
   with one voice in the house. Plumbing before the model is pipe with no water.
-- **It's fenced deliberately** (`DO NOT TOUCH THIS PHASE` in `DESIGN.md` § Users) so an
+- **It's fenced deliberately** (`DO NOT TOUCH THIS PHASE` in `docs/design.md` § Users) so an
   autonomous agent doesn't add `user_id` columns while touching the store and
   commit us to a schema before the constraints that shape it exist.