feat(prune): R2 dry-run prune shell + persist wiring, report-only

Add ReaSamplerSession::pruneDryRun enumerating the resolved current bank
folder, feeding the R1 core, and returning a PruneReport (count/bytes/list).
New pure bankRelativeForName + buildPruneReport keep spelling and tally
testable. Register forever-stable BANK_PRUNE_FOLDER action, report-only. No deletion.

tests/test_capture_paths.cpp

@@ -547,6 +547,29 @@ static void testHashWavContentDomainSeparationFromWholeFile() {
     CHECK(contentHash != wholeHash);
 }
 
+// --- bankRelativeForName spelling consistency (Phase R, R2) -----------------
+//
+// The safety-critical property: the relative spelling the prune shell derives for an
+// ENUMERATED folder entry (bankRelativeForName) must be byte-identical to the spelling
+// the capture path stored in the index (deriveBankPaths().relativePath) for the same
+// file name. A divergence here could make a referenced file look like an orphan.
+
+static void testBankRelativeForNameMatchesDerivePathSpelling() {
+    // For a file the capture path created, deriveBankPaths produced relativePath;
+    // a directory listing yields the bare file name. bankRelativeForName(name) must
+    // reproduce the SAME string, or the pure core's exact-string match misfires.
+    const BankPaths p = deriveBankPaths("/proj", "kick", "001");
+    // p.fileName is the on-disk entry name a folder enumeration would return.
+    CHECK(bankRelativeForName(p.fileName) == p.relativePath);
+}
+
+static void testBankRelativeForNameConventionAndEdge() {
+    // The convention verbatim: "reasampler_bank/<name>" (the one place the spelling lives).
+    CHECK(bankRelativeForName("a.wav") == "reasampler_bank/a.wav");
+    // Empty in -> empty out (a defensive guard; a real enumeration never yields "").
+    CHECK(bankRelativeForName("").empty());
+}
+
 int main() {
     testNormalizeSlashes();
     testNormalizeSlashesCaseFolding();
@@ -585,6 +608,8 @@ int main() {
     testHashWavContentEmptyFallsBackToHashBytes();
     testHashWavContentListMetaSkipped();
     testHashWavContentDomainSeparationFromWholeFile();
+    testBankRelativeForNameMatchesDerivePathSpelling();
+    testBankRelativeForNameConventionAndEdge();
 
     if (g_fail == 0) std::printf("capture_paths: all tests passed\n");
     else std::printf("capture_paths: %d CHECK(s) FAILED\n", g_fail);