Fold thirty-one settings pages into fifteen categories with tabs

The sidebar was a flat scan of thirty-one rows; now it reads like a
settings app. Multi-subject categories (Input, Network & Sharing,
Applications, Users & Accounts, Privacy & Security, System) carry an
Appearance-style tab strip above the page, drawn by the shell so the
leaf pages themselves are untouched. The taxonomy lives in one new
file, services/SettingsRoutes.qml; the sidebar, the strip, route
validation, search breadcrumbs, and both generators derive from it.

ShellState.settingsPage still holds leaf ids, so every deep link, IPC
call, and search result keeps working — and now lands on the exact
tab. Dictation moves out of Sound onto its own page under Input, with
a handoff back to Sound for the microphone. The strip scrolls when
System's nine tabs outgrow a tiled window. All 161 contracts pass.

Claude-Session: https://claude.ai/code/session_01Ms2FbjQy31TVf3CEvQhGM8

config/dot/quickshell/modules/settings/ShortcutsPage.qml

@@ -1,4 +1,4 @@
-// Input & Shortcuts.
+// Keyboard — layout, key behavior, and every compositor shortcut.
 //
 // The shortcut list is generated from `hyprctl binds -j` rather than typed out
 // here. The previous version was a hand-maintained array of nineteen entries
@@ -46,11 +46,11 @@ SettingsPage {
         SystemSettings.commitPreference("keyboardOptions", options.join(","));
     }
 
-    title: "Input & Shortcuts"
+    title: "Keyboard"
     lede: "The Forge mental model, carried forward into native tiling."
 
     SettingsCard {
-        title: "Keyboard"
+        title: "Layout & typing"
 
         // These were read-only text, on the grounds that a layout change needed
         // a compositor reload. It does not: setting input:kb_variant through