feat: Discard all, claude-style image pastes, large local drops, per-account / list

- Changes panel: **Discard all** beside Commit discards every non-conflicted
  file in one `discard`, after a dialog naming how many untracked files go.
- Terminal: a `claude` pane gets dropped/pasted images as bare paths (shown as
  `[Image #n]`) and other files as `@` mentions (`claudePastes`); a local
  browser's copied `file://` paths and text-drag file lists paste by path.
- `POST /api/run/drop-file`: a loopback browser outside server mode may drop
  up to 2 GB, streamed to disk; remote stays 20 MB.
- cc-config skills/commands/plugins read the USER scope of the account the
  pane runs as (S3 member home by `cwd`), never another user's or the host's
  for a non-admin without an account; the run form passes its cwd to plugins.

client/src/lib/api.ts

@@ -2210,7 +2210,8 @@ export const api = {
      * each one contributes (skills/agents/commands/hooks counts).
      * @returns {@link CcPluginsResponse} — the manifest path/status plus plugins.
      */
-    plugins: () => request<CcPluginsResponse>("/cc-config/plugins"),
+    plugins: (cwd?: string) =>
+      request<CcPluginsResponse>(`/cc-config/plugins${ccQuery(undefined, cwd)}`),
     /**
      * GET /api/cc-config/mcp - configured MCP servers, user and project-scoped.
      * @returns {@link CcMcpResponse} — servers split into `user`/`projectScoped`.