feat(core): standalone image-gen endpoint + api.ts methods (profile/password/avatar/generate-image)

- POST /api/ai/generate-image/ — project-less image generation (AITask.project nullable, no schema change),
  reuses VolcanoArk image_generation + credit reserve/charge; modes image/model/cover.
  Verified: manage.py check clean; 2 active IMAGE models present (doubao-seedream-4.5/5.0).
  (Real generation calls Volcano API + charges credit — not yet live-tested to avoid spend.)
- api.ts: updateProfile / changePassword / uploadAvatar / generateImage

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

core/frontend/src/api.ts

@@ -66,6 +66,15 @@ export const api = {
   me() {
     return request<{ user: User; team: Team }>("/api/auth/me/");
   },
+  updateProfile(payload: { name?: string; phone?: string; email?: string }) {
+    return request<{ user: User; team: Team }>("/api/auth/me/", { method: "PATCH", body: JSON.stringify(payload) });
+  },
+  changePassword(payload: { old_password: string; new_password: string }) {
+    return request<{ token: string }>("/api/auth/me/password/", { method: "POST", body: JSON.stringify(payload) });
+  },
+  uploadAvatar(formData: FormData) {
+    return request<User>("/api/auth/me/avatar/", { method: "POST", body: formData });
+  },
   logout() {
     return request<void>("/api/auth/logout/", { method: "POST" });
   },
@@ -183,6 +192,9 @@ export const api = {
   aiTasks() {
     return request<Paginated<AITask>>("/api/ai/tasks/");
   },
+  generateImage(payload: { prompt: string; mode?: "image" | "model" | "cover"; count?: number }) {
+    return request<{ assets: Asset[] }>("/api/ai/generate-image/", { method: "POST", body: JSON.stringify(payload) });
+  },
   recharge(payload: { amount: number | string; bonus?: number | string; channel?: string }) {
     return request<RechargeResult>("/api/billing/recharge/", { method: "POST", body: JSON.stringify(payload) });
   },