desktop M10.3: frontend data-source adapter seam (repo interface + rest.ts)

Extract a typed repository interface (adapters/repo.ts) from the scattered
store/view -> api.* calls, backed by adapters/rest.ts (verbatim HTTP mapping)
and selected through adapters/index.ts. Every store and the notes-facing views
now depend on `repo`, never the HTTP client directly -- the seam the offline
local source (M10.5, over Tauri invoke) plugs into next.

Behavior-preserving for web: rest.ts maps each semantic method to the exact
endpoint the code called before; query-string and multipart building moved out
of the stores/views into rest.ts (the one place that knows the URL shape).
Client-side logic (reconcile/sort/optimistic reorder/toasts) stays in the
stores. GraphView + admin SettingsView keep direct api calls -- out of the
offline-core scope (M10.5 is board/editor/capture/search/filter/labels/
checklists/reminders).

Task 1992.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01FRgehjoz7Yv8LkUfADxACm

frontend/src/stores/session.ts

@@ -1,6 +1,6 @@
 import { defineStore } from "pinia";
 import { ref } from "vue";
-import { api } from "../api/client";
+import { repo } from "../adapters";
 
 export interface User {
   id: string;
@@ -17,7 +17,7 @@ export const useSessionStore = defineStore("session", () => {
 
   async function fetchMe(): Promise<void> {
     try {
-      user.value = await api.get<User>("/api/auth/me");
+      user.value = await repo.auth.me();
     } catch {
       user.value = null;
     } finally {
@@ -26,19 +26,15 @@ export const useSessionStore = defineStore("session", () => {
   }
 
   async function login(email: string, password: string): Promise<void> {
-    user.value = await api.post<User>("/api/auth/login", { email, password });
+    user.value = await repo.auth.login(email, password);
   }
 
   async function register(email: string, password: string, displayName: string): Promise<void> {
-    user.value = await api.post<User>("/api/auth/register", {
-      email,
-      password,
-      display_name: displayName,
-    });
+    user.value = await repo.auth.register(email, password, displayName);
   }
 
   async function logout(): Promise<void> {
-    await api.post("/api/auth/logout");
+    await repo.auth.logout();
     user.value = null;
   }