feat(notificaciones): edit summary recipients in the UI

NOTIFICATION_ADMIN_EMAILS made "add Beto to the summaries" a redeploy —
the wrong unit of work for a list that changes when office staff change.

Adds `app_settings`, a key/value table for the configuration staff must
be able to change without a deploy, and `SettingsService`, which resolves
every key db -> env -> default and reports which of the three a value
came from. That ladder is what makes the move safe: a deployment behaves
exactly as before until somebody saves in the UI, and the screen can say
"this is still coming from the deployment" rather than implying somebody
chose it.

- new ability `setting:manage` (ADMIN) — deliberately above
  `notification:send`, since redirecting the audit summaries is how
  someone would quietly stop them being read
- GET/PUT /notifications/settings/admin-emails; read is open to any
  logged-in user so the UI can display the list, write is gated
- resolved per job, not cached at boot, or we would reintroduce exactly
  the restart-to-apply behaviour being removed
- a saved empty list means "nobody" and does NOT fall through to the env,
  or clearing the field would keep mailing the people just removed

Credentials stay in env — see the model doc for where the line is drawn.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

apps/api/src/settings/settings.service.ts

@@ -0,0 +1,128 @@
+import { Injectable, Logger } from "@nestjs/common";
+import { ConfigService } from "@nestjs/config";
+import { PrismaService } from "../prisma/prisma.service";
+
+/**
+ * Reader/writer for `app_settings` — the configuration staff can change
+ * without a redeploy.
+ *
+ * Every setting resolves through the same three-step ladder: the database row
+ * if an operator has set one, else the environment variable it used to live
+ * in, else a hardcoded default. That ordering is what makes this migration
+ * safe — an existing deployment keeps behaving exactly as it did until
+ * somebody edits the value in the UI, and `source` tells the UI which of the
+ * three it is looking at so "this came from the env, editing it here will
+ * take over" is visible rather than surprising.
+ */
+
+export const SETTING_KEYS = {
+  /** Comma-separated recipients of the per-job notification summary. */
+  notificationAdminEmails: "notification.adminEmails",
+} as const;
+
+/** Where a resolved value came from. Shown in the UI. */
+export type SettingSource = "db" | "env" | "default";
+
+export interface ResolvedSetting<T> {
+  value: T;
+  source: SettingSource;
+  updatedAt: Date | null;
+  updatedById: string | null;
+}
+
+/** Last resort when neither the database nor the environment says otherwise.
+ *  Matches what `NotificationsService` hardcoded before this table existed. */
+const DEFAULT_ADMIN_EMAILS = ["rmancinas@freakma.net", "mpulido@freakma.net"];
+
+/** Deliberately permissive — this rejects "not an address at all", not
+ *  "not deliverable". Only SES can tell us the latter, and a validator strict
+ *  enough to argue with is a validator that blocks a legitimate address. */
+const EMAIL_RE = /^[^\s@,]+@[^\s@,]+\.[^\s@,]+$/;
+
+export function parseEmailList(raw: string): string[] {
+  return raw
+    .split(",")
+    .map((s) => s.trim())
+    .filter(Boolean);
+}
+
+export function invalidEmails(list: string[]): string[] {
+  return list.filter((e) => !EMAIL_RE.test(e));
+}
+
+@Injectable()
+export class SettingsService {
+  private readonly logger = new Logger(SettingsService.name);
+
+  constructor(
+    private readonly prisma: PrismaService,
+    private readonly config: ConfigService,
+  ) {}
+
+  /**
+   * Recipients of the per-job summary email.
+   *
+   * Read on every send rather than cached at boot: the point of moving this
+   * out of the environment was that it changes while the app is running, and
+   * a cache would reintroduce exactly the restart-to-apply behaviour we are
+   * removing. It is one indexed primary-key lookup per sweep, not per email.
+   */
+  async notificationAdminEmails(): Promise<ResolvedSetting<string[]>> {
+    const row = await this.read(SETTING_KEYS.notificationAdminEmails);
+    if (row) {
+      const parsed = parseEmailList(row.value);
+      // An empty stored value is a legitimate choice — "send no summaries" —
+      // and must not silently fall through to the env or the defaults, or an
+      // operator who cleared the field would keep receiving mail.
+      return {
+        value: parsed,
+        source: "db",
+        updatedAt: row.updatedAt,
+        updatedById: row.updatedById,
+      };
+    }
+
+    const env = this.config.get<string>("NOTIFICATION_ADMIN_EMAILS");
+    if (env && env.trim()) {
+      return {
+        value: parseEmailList(env),
+        source: "env",
+        updatedAt: null,
+        updatedById: null,
+      };
+    }
+
+    return {
+      value: [...DEFAULT_ADMIN_EMAILS],
+      source: "default",
+      updatedAt: null,
+      updatedById: null,
+    };
+  }
+
+  /** Persist the summary recipients. An empty list is stored as an empty
+   *  string and means "nobody" — see the read path above. */
+  async setNotificationAdminEmails(
+    emails: string[],
+    userId: string,
+  ): Promise<ResolvedSetting<string[]>> {
+    await this.write(
+      SETTING_KEYS.notificationAdminEmails,
+      emails.join(","),
+      userId,
+    );
+    return this.notificationAdminEmails();
+  }
+
+  private read(key: string) {
+    return this.prisma.appSetting.findUnique({ where: { key } });
+  }
+
+  private async write(key: string, value: string, userId: string) {
+    await this.prisma.appSetting.upsert({
+      where: { key },
+      create: { key, value, updatedById: userId },
+      update: { value, updatedById: userId },
+    });
+  }
+}