Retire MPE scaffold; stand up reaper_reasampler pure-core skeleton

Rename CMake project/module to reaper_reasampler, delete mpe_model/mpe_view,
add minimal pure bank_model lib + placeholder CTest. main.cpp loads, logs to
console, keeps the action-registration seam commented with the forever-stable
CEREBELLUM_REASAMPLER_ action-id prefix.

src/bank_model.h

@@ -0,0 +1,17 @@
+#pragma once
+// bank_model — the HEART of ReaSampler, deliberately free of any REAPER type so
+// it compiles and unit-tests OUTSIDE the DAW. It owns the per-project sample
+// bank: the `Sample` metadata struct and the `BankIndex` (add / remove / query /
+// tier moves / dedup-by-hash + JSON round-trip).
+//
+// Milestone 0 placeholder: this is a minimal compiling stub sufficient to stand
+// up the pure static lib and its CTest. The full data model (Sample field set,
+// BankIndex operations, JSON) is Milestone 1 — see PLAN.md / CONTEXT.md §Data model.
+
+namespace reasampler {
+
+// M0 placeholder — replaced by the real `Sample` / `BankIndex` in Milestone 1.
+// Returns the on-disk schema version the bank_model serializes to.
+int bankModelVersion();
+
+} // namespace reasampler