docs: 1.0 documentation restructure

Split root CLAUDE.md into 19 per-directory files scoped to their source area.
Roll v0 history into docs/ARCHIVE.md; retire CONTEXT.md, CONTEXT-ARCHIVE.md,
PLAN.md, COMPLETED.md. Move plan docs under docs/. Rescue 9 live deferrals
into docs/TODO.md.

docs/product/audit-notes/q-w0-t3-env-constants.md

@@ -2,9 +2,9 @@
 
 Static analysis, 2026-07-28, branch `pq-w0-audit`. Scope: any value stored in an
 environment-coupled domain — frames, sample rate, DPI, pixels, tick cadence — that should be
-stored **rate-free / device-free and resolved at the point of use** (PLAN.md §Q-W0 env-coupled
-bullet; `docs/product/code-organization.md` §2c.3; the load-bearing `sample_map` seconds
-invariant). Findings are domain-modeling calls, not "rescale by rate" patches. The judgment bar
+stored **rate-free / device-free and resolved at the point of use** (`docs/product/code-organization.md`
+§2c.3 env-coupled bullet; the load-bearing `sample_map` seconds invariant, documented in
+`src/core/instrument/CLAUDE.md`). Findings are domain-modeling calls, not "rescale by rate" patches. The judgment bar
 applied: a finding requires (a) an env-coupled *stored* domain AND (b) an environment that can
 actually change under it. Frame counts computed transiently from seconds at the use site are
 correct and are not reported.
@@ -63,7 +63,7 @@ fix-now findings in those files must be remediated in Q-W0 itself.
   normalize the Trigger fade-in/out knobs.
 - **Stored vs. correct domain:** the fade **storage** domain (int64 SOURCE frames, persisted in
   the zones payload) is settled and correct — a source-timeline fact, invariant under project-
-  rate change (PLAN.md §S15). The *UI ceiling*, however, encodes a wall-clock intent ("2-second
+  rate change (`docs/ARCHIVE.md` §S15). The *UI ceiling*, however, encodes a wall-clock intent ("2-second
   max fade throw") as a frame count at an assumed 44.1 kHz source. `88200` is a rate-derived
   literal in `src/`, brushing the no-hardcoded-rate ruling even though it never touches disk.
 - **What breaks when the environment shifts:** the environment here is the **source file's
@@ -165,7 +165,7 @@ fix-now findings in those files must be remediated in Q-W0 itself.
   `SampleRefs` (paths + root/loop/channels intrinsics), `instanceGuid` — all rate-free or
   file-fact domains. Clean.
 - **Trigger `fadeInFrames`/`fadeOutFrames`/`startPoint`/`SampleLoop.start/end` persisted as
-  int64 SOURCE frames:** deliberate, settled source-timeline facts (PLAN.md §S15;
+  int64 SOURCE frames:** deliberate, settled source-timeline facts (`docs/ARCHIVE.md` §S15;
   `bank_model.h:66-72` documents the loop rationale) — frames *of the file* are invariant under
   project-rate change; the file's own rate is stored alongside and resolved at decode. Correct
   domain, not a finding.