feat(admin): open controller-link settings entries from the settings index

A settings entry with a controller opens that controller's route from
its card (settingsPath); singleton cards still open /settings/<code>.
On a linked controller with no navigation entry of its own the rail
marks Settings current, the breadcrumbs read Settings > entry label
(plus the record title on record and create routes) and the page title
uses the entry label. The settings docs describe the admin behaviour;
the embedded admin shell is rebuilt.

admin/src/state/useSettings.ts

@@ -1,7 +1,10 @@
 // Settings pages the admin may manage (D-21), server-filtered like the
 // navigation. The rail shows "Ustawienia" only when this list is non-empty.
+// An entry is either a singleton settings form (/settings/<code>) or a link
+// that opens an admin controller (its `controller` is set).
 import { computed, readonly, ref } from 'vue'
 import { api } from '../api/client'
+import { controllerPath } from '../app/controllerRoutes'
 import type { SettingsEntry } from '../api/types'
 
 const entries = ref<SettingsEntry[]>([])
@@ -24,6 +27,25 @@ export function settingsEntry(code: string): SettingsEntry | null {
   return entries.value.find((entry) => entry.code === code) ?? null
 }
 
+/**
+ * Route a settings entry opens: its controller for a link entry (the index
+ * when the ID is malformed), otherwise its singleton form.
+ */
+export function settingsPath(entry: SettingsEntry): string {
+  if (entry.controller) {
+    return controllerPath(entry.controller) ?? '/settings'
+  }
+  return `/settings/${encodeURIComponent(entry.code)}`
+}
+
+/** The link entry that opens the given controller, if any. */
+export function settingsLinkFor(controllerId: string | null): SettingsEntry | null {
+  if (!controllerId) {
+    return null
+  }
+  return entries.value.find((entry) => entry.controller !== '' && entry.controller === controllerId) ?? null
+}
+
 /** Entries grouped by category, categories in first-seen order, by order. */
 export const settingsGroups = computed(() => {
   const sorted = entries.value
@@ -43,5 +65,5 @@ export const settingsGroups = computed(() => {
 })
 
 export function useSettings() {
-  return { settings, hasSettings, settingsGroups, loadSettings, settingsEntry }
+  return { settings, hasSettings, settingsGroups, loadSettings, settingsEntry, settingsPath, settingsLinkFor }
 }