Remediate Phase P render-in-place review findings

Fix the ProjectMedia refusal path's false bank claims and file relocation, an unreachable-undo idiom, and eight comment/doc accuracy issues.

src/core/capture/capture_name.cpp

@@ -90,8 +90,10 @@ std::string captureTrackName(const std::string& sourceName) {
     const std::string prefix(kCaptureTrackPrefix);
     // A source with no readable name yields the bare word rather than a trailing
     // space; both spellings are fixed points, which is what makes the whole function
-    // one (a track named exactly "Capture" must not become "Capture Capture").
-    const std::string bare = prefix.substr(0, prefix.size() - 1);
+    // one (a track named exactly "Capture" must not become "Capture Capture"). Read
+    // from kCaptureTrackPrefixBare rather than chopped off prefix, so the two names
+    // can't drift out of sync with each other (both expand from the same header token).
+    const std::string bare = kCaptureTrackPrefixBare;
 
     if (sourceName.empty()) return bare;
     if (sourceName == bare) return sourceName;