Fix dead Cmd+/ shortcut for In-App Help; rebind to Ctrl+Cmd+H

Cmd+/ was never reaching the "In-App Help" menu item — AppKit
auto-reserves Cmd+/ to open/focus the app's own Help menu (same
mechanism as Cmd+?), silently pre-empting any custom binding on that
combo, exactly like the earlier Cmd+H (Hide Application) conflict.

Verified live with computer-use before landing on Ctrl+Cmd+H:
Option+Cmd+/ has unpredictable menu-glyph rendering and didn't fire;
Option+Cmd+H is macOS's reserved "Hide Others" shortcut (visibly hid
other app windows when tested). Ctrl+Cmd+H showed no OS-level effect
and correctly opens the panel.

HelpView's search bar was already fully implemented and working —
this was purely a matter of the shortcut never reaching it.

oAI/Resources/oAI.help/Contents/Resources/en.lproj/index.html

@@ -1526,7 +1526,7 @@ Whenever the user asks you to translate something, translate it to Norwegian Bok
                     <dt><kbd>⌘,</kbd></dt>
                     <dd>Open Settings</dd>
 
-                    <dt><kbd>⌘/</kbd></dt>
+                    <dt><kbd>⌃⌘H</kbd></dt>
                     <dd>Show in-app Help</dd>
 
                     <dt><kbd>⌘?</kbd></dt>