docmontage: end-tag overlay default + Chirp 3 HD as default TTS voice

End-tag now composited over final body footage (ProRes 4444 with alpha)
instead of concatenated as a black card. Updated idea-director,
edit-director, compose-director, and pipeline manifest with overlay-first
instructions. Default Google TTS voice changed from Neural2-D to
Chirp3-HD-Orus across tool code and docs.

remotion-composer/src/Root.tsx

@@ -220,6 +220,24 @@ export const Root: React.FC = () => {
           fadeOutSeconds: 0.6,
         } as EndTagProps}
       />
+      <Composition
+        id="EndTagOverlay"
+        component={EndTag}
+        // 8.19s at 30fps = 246 frames. Render CLI can override via --props.
+        // Intended to be composited on top of body footage, not concat'd.
+        durationInFrames={246}
+        fps={30}
+        width={1920}
+        height={1080}
+        defaultProps={{
+          text: "EARN THE LIGHT.",
+          palette: "cool_offwhite_on_black",
+          fadeInSeconds: 1.0,
+          holdSeconds: 5.69,
+          fadeOutSeconds: 1.5,
+          overlay: true,
+        } as EndTagProps}
+      />
     </>
   );
 };

remotion-composer/src/components/EndTag.tsx

@@ -13,6 +13,12 @@ export interface EndTagProps {
   fadeInSeconds?: number;
   holdSeconds?: number;
   fadeOutSeconds?: number;
+  // Overlay mode: render on a transparent background so the tag can be
+  // composited on top of the body footage in post, instead of being
+  // concatenated as a standalone black card. When `overlay=true` the
+  // AbsoluteFill drops its background fill — caller is responsible for
+  // rendering with an alpha-capable codec (VP9/WebM or ProRes 4444).
+  overlay?: boolean;
 }
 
 const PALETTES = {
@@ -49,6 +55,7 @@ export const EndTag: React.FC<EndTagProps> = ({
   fadeInSeconds = 0.6,
   holdSeconds = 4.3,
   fadeOutSeconds = 0.6,
+  overlay = false,
 }) => {
   const frame = useCurrentFrame();
   const { fps } = useVideoConfig();
@@ -113,7 +120,7 @@ export const EndTag: React.FC<EndTagProps> = ({
   return (
     <AbsoluteFill
       style={{
-        backgroundColor: pal.background,
+        backgroundColor: overlay ? "transparent" : pal.background,
         justifyContent: "center",
         alignItems: "center",
       }}