M10: provenance populate + re-capture from source (bank-only)

Pure provenance core (recipe fingerprint, FX-chain identity, parent
detection) + shell reads; capture stamps provenance on resample-from-sample;
re-capture regenerates a provenanced sample from its source, never touching
the timeline. Adds BankIndex/BankBook in-place update. CTest-covered.

src/bank_model.cpp

@@ -93,6 +93,17 @@ bool BankIndex::remove(const std::string& id) {
     return false;
 }
 
+bool BankIndex::updateInPlace(const std::string& id, const Sample& updated) {
+    if (isAbsolutePath(updated.relativePath)) return false;  // invariant still holds
+    for (auto& s : samples_) {
+        if (s.id == id) {
+            s = updated;  // replace in place — position (insertion order) preserved
+            return true;
+        }
+    }
+    return false;
+}
+
 const Sample* BankIndex::query(const std::string& id) const {
     for (const auto& s : samples_)
         if (s.id == id) return &s;