Fix extension zip nesting so Load unpacked works

Zip the extension's files at the archive root (manifest.json at top level) instead of
under an extension/ subfolder, so the unzipped folder can be selected directly in
"Load unpacked". Clarify the install step (select the folder containing manifest.json).

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

app.py

@@ -33,14 +33,15 @@ EXTENSION_DIR = os.path.join(APP_DIR, "extension")
 def _build_extension_zip() -> str | None:
     """Zip the bundled browser extension for one-click download; return the .zip path.
 
-    Produces an archive whose top-level folder is ``extension/`` so it unzips to a
-    ready-to-"Load unpacked" directory. Returns None if the folder isn't present.
+    The extension's files (manifest.json, etc.) sit at the **root** of the archive, so the
+    unzipped folder directly contains manifest.json and can be selected as-is in
+    "Load unpacked". Returns None if the folder isn't present.
     """
     if not os.path.isdir(EXTENSION_DIR):
         return None
     out_base = os.path.join(tempfile.gettempdir(), "tutorialmaker-extension")
     try:
-        return shutil.make_archive(out_base, "zip", root_dir=APP_DIR, base_dir="extension")
+        return shutil.make_archive(out_base, "zip", root_dir=EXTENSION_DIR)
     except Exception:
         return None
 

extension/README.md

@@ -12,9 +12,12 @@ It just surfaces these for one-click copy; it sends nothing anywhere.
 
 ## Install (unpacked)
 
-1. Open `chrome://extensions` (or `edge://extensions`).
+1. Open `chrome://extensions` (or `edge://extensions`, `comet://extensions`).
 2. Turn on **Developer mode** (top-right).
-3. Click **Load unpacked** and select this `extension/` folder.
+3. Click **Load unpacked** and select the folder that **directly contains
+   `manifest.json`** — i.e. the unzipped download folder, or this `extension/` folder if
+   you cloned the repo. (If you see a "Manifest file is missing" error, you selected a
+   parent folder — go one level deeper to the one holding `manifest.json`.)
 
 > Firefox: it's MV3-compatible in spirit, but Firefox needs a `background.scripts` entry
 > and a `browser_specific_settings` block instead of `service_worker`. Minor manifest