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

tests/quickshell/settings-search-contract

@@ -104,12 +104,20 @@ EXTRACT
 )
 [[ "$missing" -eq 0 ]] || fail "$missing schema label(s) are not findable by search"
 
-# ── Results only ever route to pages the shell can open ──────────────────────
-allowed="$(grep -oE 'const allowed = \[[^]]*\]' "$repo_dir/config/dot/quickshell/services/ShellState.qml" \
-    | grep -oE '"[a-z-]+"' | tr -d '"' | sort -u)"
-for query in wallpaper blur timezone screenshot pointer lock volume gaps; do
+# ── Results only ever route to leaves the shell can open ─────────────────────
+# A search result carries a leaf id, never a category: it has to land on the
+# exact tab holding the setting, not on whichever tab that category opens
+# first. SettingsRoutes is where the leaves are declared -- a tabless category
+# is one, and so is every tab.
+routes="$repo_dir/config/dot/quickshell/services/SettingsRoutes.qml"
+leaves="$( {
+    grep -oE '\{ page: "[a-z-]+", label: "[^"]*", icon: "[^"]*", tabs: \[\] \}' "$routes"
+    grep -oE '\{ page: "[a-z-]+", label: "[^"]*" \}' "$routes"
+} | sed -E 's/\{ page: "([a-z-]+)".*/\1/' | sort -u)"
+[[ -n "$leaves" ]] || fail 'no leaf pages could be read from SettingsRoutes, so this proves nothing'
+for query in wallpaper blur timezone screenshot pointer lock volume gaps dictation; do
     page="$(find_top "$query" | jq -r .topPage)"
-    grep -qx "$page" <<<"$allowed" || fail "search routed '$query' to unknown page '$page'"
+    grep -qx "$page" <<<"$leaves" || fail "search routed '$query' to '$page', which is not a page anyone can land on"
 done
 
 trap - EXIT