docs: archive Phase V (V1-V4) to COMPLETED; reconcile CLAUDE.md

Phase V landed: app_version module, ext-state version stamp, show-version
action, beta-in-isolation channel build. CLAUDE.md gains the module entry,
version key, test target, and beta-build note.

PLAN.md

@@ -238,46 +238,6 @@ CONTEXT.md §Prune (Settled forks).
 
 ---
 
-# Phase V — Versioning & release (release-milestone pillar, own lettered namespace)
-
-> **New pillar, own lettered namespace.** Version scheme + beta side-channel — the
-> release-deployment path M11 forward-implies but that had no phase or points.
-> Namespaced **`V` (Versioning)** alongside `M`/`D`/`B`/`R` because it is a distinct
-> concern (build identity + channel isolation) that touches CMake, `main.cpp`'s
-> forever-stable command-id contract, and the `"reasampler"` ext-state — not a
-> capture step. Product framing + the full option analysis: `docs/product/versioning-
-> and-release.md`. **Forks V1–V4 SETTLED (Daniel, 2026-07-26)** — semver via
-> `project(VERSION)` + ext-state version stamp prioritized first-wave; plain `-beta`
-> suffix; console line + panel readout (about-box deferred); and **beta ships as a
-> separate, fully isolated coexisting binary (beta-in-isolation)** — a reversal of the
-> note's original one-at-a-time recommendation. Deploy/CD wiring (now two named
-> artifacts per platform) hands off to dev-ops. Build-scoped points to be drawn up.
-
-## Settled decisions (Daniel, 2026-07-26 — see `docs/product/versioning-and-release.md`)
-- **V1 — version scheme: APPROVED as recommended.** Semver, single source of truth in
-  CMake `project(reaper_reasampler VERSION x.y.z)`, threaded into the binary. **The
-  `"reasampler"` ext-state writing-version stamp is prioritized to the first wave, not
-  deferred** — every project saved without the stamp is harder to migrate later, so
-  the migration seam lands early.
-- **V2 — beta suffix: plain `-beta`.** `project(VERSION)` owns the release triple; beta
-  carries a `-beta` suffix. `git describe` decoration considered and rejected for
-  legibility.
-- **V3 — user-visible home: recommendation accepted.** Startup console line
-  (`"ReaSampler x.y.z loaded"`) + a bank-panel version/channel readout; about-box
-  deferred. Panel placement is the residual polish call.
-- **V4 — beta channel shape: BETA-IN-ISOLATION (full coexistence).** *Reverses the
-  original recommendation.* Beta ships as a **separate binary** (`reaper_reasampler_
-  beta`) with an **isolated ext-state namespace** (distinct from stable's
-  `"reasampler"` — a beta cannot corrupt a stable project's saved state) and an
-  **isolated forever-stable command-id prefix** (beta/stable keybindings don't
-  collide), so both install and run side-by-side. Built through a compile-time channel
-  flag (`-DREASAMPLER_CHANNEL=beta`) as the mechanism. **Two permanent commitments
-  locked in:** a second forever-stable command-id prefix and a second ext-state
-  namespace. **Dev-ops:** the build now produces two named artifacts (stable + beta)
-  per platform.
-
----
-
 # Phase S — MIDI-playback instrument (native VST3 sampler; a second build artifact)
 
 > **New pillar, own lettered namespace, and — uniquely — a second build artifact.**