feat: add Google Search Console integration UI

Search Console page with overview cards, top queries/pages tables,
and query↔page drill-down. Integrations tab in Settings for
connect/disconnect flow. New Search tab in site navigation.

lib/api/gsc.ts

@@ -0,0 +1,79 @@
+import apiRequest from './client'
+
+// ─── Types ──────────────────────────────────────────────────────────
+
+export interface GSCStatus {
+  connected: boolean
+  google_email?: string
+  gsc_property?: string
+  status?: 'active' | 'syncing' | 'error'
+  error_message?: string | null
+  last_synced_at?: string | null
+  created_at?: string
+}
+
+export interface GSCOverview {
+  total_clicks: number
+  total_impressions: number
+  avg_ctr: number
+  avg_position: number
+  prev_clicks: number
+  prev_impressions: number
+  prev_avg_ctr: number
+  prev_avg_position: number
+}
+
+export interface GSCDataRow {
+  query: string
+  page: string
+  impressions: number
+  clicks: number
+  ctr: number
+  position: number
+}
+
+export interface GSCQueryResponse {
+  queries: GSCDataRow[]
+  total: number
+}
+
+export interface GSCPageResponse {
+  pages: GSCDataRow[]
+  total: number
+}
+
+// ─── API Functions ──────────────────────────────────────────────────
+
+export async function getGSCAuthURL(siteId: string): Promise<{ auth_url: string }> {
+  return apiRequest<{ auth_url: string }>(`/sites/${siteId}/integrations/gsc/auth-url`)
+}
+
+export async function getGSCStatus(siteId: string): Promise<GSCStatus> {
+  return apiRequest<GSCStatus>(`/sites/${siteId}/integrations/gsc/status`)
+}
+
+export async function disconnectGSC(siteId: string): Promise<void> {
+  await apiRequest(`/sites/${siteId}/integrations/gsc`, {
+    method: 'DELETE',
+  })
+}
+
+export async function getGSCOverview(siteId: string, startDate: string, endDate: string): Promise<GSCOverview> {
+  return apiRequest<GSCOverview>(`/sites/${siteId}/gsc/overview?start_date=${startDate}&end_date=${endDate}`)
+}
+
+export async function getGSCTopQueries(siteId: string, startDate: string, endDate: string, limit = 50, offset = 0): Promise<GSCQueryResponse> {
+  return apiRequest<GSCQueryResponse>(`/sites/${siteId}/gsc/top-queries?start_date=${startDate}&end_date=${endDate}&limit=${limit}&offset=${offset}`)
+}
+
+export async function getGSCTopPages(siteId: string, startDate: string, endDate: string, limit = 50, offset = 0): Promise<GSCPageResponse> {
+  return apiRequest<GSCPageResponse>(`/sites/${siteId}/gsc/top-pages?start_date=${startDate}&end_date=${endDate}&limit=${limit}&offset=${offset}`)
+}
+
+export async function getGSCQueryPages(siteId: string, query: string, startDate: string, endDate: string): Promise<GSCPageResponse> {
+  return apiRequest<GSCPageResponse>(`/sites/${siteId}/gsc/query-pages?query=${encodeURIComponent(query)}&start_date=${startDate}&end_date=${endDate}`)
+}
+
+export async function getGSCPageQueries(siteId: string, page: string, startDate: string, endDate: string): Promise<GSCQueryResponse> {
+  return apiRequest<GSCQueryResponse>(`/sites/${siteId}/gsc/page-queries?page=${encodeURIComponent(page)}&start_date=${startDate}&end_date=${endDate}`)
+}