chore: migrate mail themes to shared framework and locked upstream inputs

docs/images/README.md

@@ -1,5 +1,7 @@
 # Style Preview Images
 
+> Images show the current snapshot-driven source build. Historical release archives retain their original templates and are not replaced by these screenshots.
+
 Place theme style screenshots of **Desktop** in PNG format here, captured from the [local preview](../../preview/index.html).
 
 ## Naming Convention
@@ -19,9 +21,11 @@ To ensure screenshots can be displayed in the README, please follow these size r
 
 ## How to Capture
 
-1. Start the dev server: `cd tools && go run . dev` (opens http://localhost:3456 in your browser)
-2. For each style, select the **"Activate Account"** template and **"Modern"** client mode in **"Desktop"**
+1. Start the dev server: `cd tools && go run . dev` and open http://127.0.0.1:3456 in your browser
+2. For each style, select the **"Register Notify"** template and **"Modern"** view, **"en-US"** language and **"Desktop"** viewport; close the floating inspector
 3. Take a screenshot of the rendered email (600px width recommended)
 4. Save as `<style-name>.png` in this directory
 
 > For a source clone, run `cd tools && go run . preview all`, return to the repository root, then open `preview/index.html` directly.
+
+For automated capture, install the optional dependencies in `tools/qa` and run `node preview.cjs --update-gallery` there. Set `BROWSER_EXECUTABLE_PATH` when using an installed Chrome/Edge instead of Playwright's bundled Chromium.