Reflect M0 landing in docs

Retarget README to ReaSampler and current build targets; reconcile
CLAUDE.md repo-identity + targets table to reaper_reasampler; archive
Milestone 0 from PLAN.md into new COMPLETED.md.

README.md

@@ -0,0 +1,83 @@
+# ReaSampler
+
+A native C++ REAPER extension that captures any arbitrary audio source into a
+per-project **sample bank** (cached files + a docked grid), decoupled from the
+arrange view, with keyboard/MIDI-bindable capture and placement. Built as a
+precision tool: deterministic, non-destructive, no clutter.
+
+This is a **skeleton**: the loading contract, build system, and the testable
+pure-core library are wired up. The bank panel, capture backend, and remaining
+module set are stubbed with clearly marked seams.
+
+## Layout
+
+    src/main.cpp            The REAPER<->extension contract: the single file that
+                            #defines REAPERAPI_IMPLEMENT, resolves API pointers,
+                            and holds the action-registration seam (commented,
+                            ready to reinstate under the CEREBELLUM_REASAMPLER_
+                            prefix). Logs "ReaSampler loaded." on startup.
+    src/bank_model.{h,cpp}  Pure, REAPER-free core: the Sample metadata struct and
+                            BankIndex (add / remove / query / tier moves /
+                            dedup-by-hash + JSON round-trip). This is the heart;
+                            everything else hangs off it. Currently an M0
+                            placeholder — the full implementation is Milestone 1.
+    tests/test_bank_model.cpp  Standalone tests for bank_model — no REAPER needed.
+    vendor/                 git submodules go here (see below).
+
+Target module set (milestones ahead — see PLAN.md):
+
+    bank_model   Sample metadata + BankIndex + JSON (pure)
+    peaks        Waveform min/max bins from raw PCM (pure)
+    capture      ICaptureBackend: OfflineRenderBackend + RealtimeRecordBackend
+    insert       InsertMedia-based placement (explicit tempo-conform flag)
+    bank_panel   Docked LICE-drawn grid: thumbnails, audition, multi-select
+    persist      Project ext state <-> bank_model JSON; project-relative paths
+    actions      Bindable capture / placement / slot action family
+
+## One-time setup
+
+    git submodule update --init
+
+Vendors two submodules:
+- `vendor/reaper-sdk` — `sdk/reaper_plugin.h`, `sdk/reaper_plugin_functions.h`, SWELL headers
+- `vendor/WDL` — WDL utilities and the SWELL cross-platform Win32 layer
+
+## Build
+
+    cmake -B build -S .
+    cmake --build build
+
+Targets:
+- `bank_model_tests` — run with `ctest --test-dir build` (or run the binary).
+  This is your fast loop: iterate the pure core without touching REAPER.
+- `reaper_reasampler` — the extension binary.
+
+### macOS / Linux dialog resources
+
+When `bank_panel` is added (Milestone 5), `resource.rc` will need SWELL's resgen
+once (Win32 compiles it directly). Generate the SWELL dialog source and add it to
+the non-Windows build:
+
+    php vendor/WDL/WDL/swell/mac_resgen.php src/resource.rc   # macOS
+    # (Linux uses the same generated output.)
+
+Then add the generated file to the `APPLE` / Linux `target_sources` blocks in
+CMakeLists.txt. The SWS extension's build is the canonical reference if you get
+stuck here — it's the fiddliest step and only bites once.
+
+## Install / test
+
+Copy the built binary into REAPER's `UserPlugins/` folder
+(Options -> Show REAPER resource path), then **restart REAPER** (extensions load
+at startup; there is no hot reload). The extension logs "ReaSampler loaded." to
+the REAPER console on startup; no actions are registered yet.
+
+Debug by attaching your debugger to the REAPER process. `ShowConsoleMsg` is a
+quick printf.
+
+## Where to build next
+
+See `PLAN.md` for the full milestone roadmap and `TODO.md` for the near-term slice.
+The current first work is **Milestone 1** — flesh out `bank_model`: define the full
+`Sample` field set, implement `BankIndex` (add / remove / query / tier / dedup),
+add JSON serialize/deserialize, and drive it all through the existing CTest harness.