A stale useUiScale comment, and a usage line for doc-links.py (#376)

Two small fixes.

- `OptionsFrame.xml`: the comment on the missing Use UI Scale checkbox said benilla has no `useUiScale`. It is registered at "0" and never read, which is why the UI scale always applies.
- `scripts/doc-links.py`: `--help` and `-h` print the usage in the module doc instead of running the full `cargo doc` pass.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>

crates/benilla-app/assets/ui/OptionsFrame.xml

@@ -1808,8 +1808,9 @@
                                         </Frame>
                                     </Frames>
                                 </Frame>
-                                <!-- No useUiScale checkbox, which 1.12 has: benilla has no
-                                     useUiScale, so the UI scale always applies. -->
+                                <!-- No useUiScale checkbox, which 1.12 has: benilla registers
+                                     useUiScale but never reads it, so the UI scale always
+                                     applies. -->
                                 <Frame name="$parentGraphics" hidden="true">
                                     <Anchors>
                                         <Anchor point="TOPLEFT"/>

scripts/doc-links.py

@@ -55,6 +55,9 @@ def declared_names() -> set[str]:
 
 
 def main() -> int:
+    if any(a in ("-h", "--help") for a in sys.argv[1:]):
+        print(__doc__.strip())
+        return 0
     report = "--report" in sys.argv
     text = run_rustdoc()
     found = re.findall(r"warning: unresolved link to `([^`]+)`\n\s*--> ([^\s:]+):(\d+)", text)