Route every extension bank-directory lookup through one bankRootOf seam

The pure bankRootFor(rppPath, unsavedRoot) and the shell bankRootOf(ReaProject*) replace eleven hand-rolled .rpp-parent derivations. No unsaved root is supplied yet, so behaviour and refusals are unchanged. Save-As relocation now reads the stored lastBankRoot_.

src/shell/actions/ingest.cpp

@@ -17,10 +17,11 @@
 #include "core/model/bank_book.h"           // BankBook, Bank, activeBankId / activeIndex
 #include "core/model/bank_model.h"          // Sample, AddResult, findByHash
 #include "shell/panel/panel_input.h"  // bankPanelRefresh
-#include "core/capture/capture_paths.h"       // deriveBankPaths / projectDirOfRpp
+#include "core/capture/capture_paths.h"       // deriveBankPaths
 #include "core/util/file_bytes.h"  // shared whole-file loader
 #include "core/wire/instrument_drop.h"     // pure buildInstrumentDropPreset (.vstpreset image for a sampleId)
 #include "shell/actions/instrument_drop_win.h" // shell loadInstrumentOntoTrack (FX add+apply, no own undo block)
+#include "shell/persist/bank_root.h"
 #include "shell/persist/session.h"             // ReaSamplerSession
 #include "shell/undo/undo_block.h"             // the ONE undo-block opener
 
@@ -29,7 +30,6 @@
 #include "reaper_plugin.h"       // reaper_plugin_info_t, gaccel_register_t (full defs)
 
 #define REAPERAPI_MINIMAL
-#define REAPERAPI_WANT_EnumProjects
 #define REAPERAPI_WANT_ShowConsoleMsg
 #define REAPERAPI_WANT_MediaExplorerGetLastPlayedFileInfo
 #define REAPERAPI_WANT_PCM_Source_CreateFromFile
@@ -47,7 +47,6 @@ using capture::buildFloat32Wav;
 using capture::deriveBankPaths;
 using capture::hashWavContent;
 using capture::parseWavLayout;
-using capture::projectDirOfRpp;
 using capture::WavLayout;
 using util::readFileBytes;
 using version::channelActionName;
@@ -79,14 +78,6 @@ std::string g_idImportStr;
 std::string g_idImportMxStr;
 std::string g_labelImportStr;
 
-// Forward-slashed, no trailing slash. Empty for an unsaved/no-active project, which
-// makes the import refuse to place a file (relative-paths invariant, no fallback).
-std::string currentProjectDir() {
-    std::vector<char> buf(4096, '\0');
-    EnumProjects(-1, buf.data(), static_cast<int>(buf.size()));
-    return projectDirOfRpp(std::string(buf.data()));
-}
-
 // Writes a byte buffer to a file. Returns true on success. The caller is responsible for
 // ensuring the directory exists before calling.
 bool writeFileBytes(const std::string& path, const std::vector<std::uint8_t>& bytes) {
@@ -170,7 +161,8 @@ ImportResult importFileIntoActiveBank(const std::string& absoluteSourcePath) {
         return out;
     }
 
-    const std::string projectDir = currentProjectDir();
+    // Empty refuses to place a file: relative-paths invariant, no fallback.
+    const std::string projectDir = bankRootOf(nullptr);
     if (projectDir.empty()) {
         out.message = "no saved project, so the bank has no location -- save the "
                       "project first";