Modernize email: Gmail OAuth2 sending, configured under Settings

Retire env-var SMTP basic-auth and send the contact form through Gmail over
OAuth2 (SMTP XOAUTH2), configured in Admin -> Settings -> Email via an in-app
"Connect Gmail" consent flow. Reuses the existing google SSO OAuth client; the
captured refresh token is stored AES-GCM-encrypted (write-only over the API,
never returned), mirroring the auth-provider and Discord-bot secret patterns.

- schema: new email_config singleton table (mirrors bot_config)
- model: emailConfig.{db,model} with encrypted refresh token + getSafe/getWithSecret
- mailer: nodemailer OAuth2 transport (client id/secret from the google provider
  row), contact recipient = contact_email setting, mailto: fallback preserved,
  plus sendTest()
- routes/controller: /admin/email config, connect start+callback (ssoState CSRF
  + PKCE), test, disconnect
- client: EmailDelivery section on the Settings page + api methods; Settings copy
  now spells out that contact_email is the delivery recipient
- docs/env: drop SMTP_*/CONTACT_TO from env examples; update README/BACKEND_DESIGN
- tests: emailConfig.model + mailer suites (8 new; full suite 142 pass)

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01XKeCQEJZr1AFJN4Bgcmvh3

server/src/router/v1/admin/admin.routes.js

@@ -10,6 +10,7 @@ const account = require('./account.controller')
 const botActivity = require('./botActivity.controller')
 const authProviders = require('./authProviders.controller')
 const discordBot = require('./discordBot.controller')
+const emailConfig = require('./emailConfig.controller')
 const moderation = require('./moderation.controller')
 const { isLoggedIn, requireRole } = require('../../../utils/auth')
 const noindex = require('../../../middleware/noindex')
@@ -575,6 +576,84 @@ adminRouter.put(
   discordBot.saveConfig,
 )
 
+// ── Email delivery (Gmail OAuth2, admin only) ─────────────────────────
+// Modern replacement for env SMTP: the refresh token is captured by the connect
+// flow and is write-only over this API (stored encrypted, never returned).
+adminRouter.get(
+  '/email/config',
+  // #swagger.tags = ['Admin · Email']
+  // #swagger.summary = 'Get email delivery config + status (admin only)'
+  // #swagger.security = [{ "cookieAuth": [] }, { "bearerAuth": [] }]
+  /* #swagger.responses[200] = { description: 'Config (refresh token stripped) + status', content: { "application/json": { schema: { type: "object", additionalProperties: true } } } } */
+  /* #swagger.responses[401] = { description: 'Not authenticated', content: { "application/json": { schema: { $ref: "#/components/schemas/Error" } } } } */
+  /* #swagger.responses[403] = { description: 'Admin role required', content: { "application/json": { schema: { $ref: "#/components/schemas/Error" } } } } */
+  adminOnly,
+  emailConfig.getConfig,
+)
+adminRouter.put(
+  '/email/config',
+  // #swagger.tags = ['Admin · Email']
+  // #swagger.summary = 'Update email delivery config (admin only)'
+  // #swagger.description = 'Set the From display name and enabled toggle. Enabling requires a connected Gmail account.'
+  // #swagger.security = [{ "cookieAuth": [] }, { "bearerAuth": [] }]
+  /* #swagger.requestBody = { content: { "application/json": { schema: { type: "object", properties: { senderName: { type: "string" }, enabled: { type: "boolean" } } } } } } */
+  /* #swagger.responses[200] = { description: 'Updated config', content: { "application/json": { schema: { type: "object", additionalProperties: true } } } } */
+  /* #swagger.responses[400] = { description: 'Cannot enable before connecting a mailbox', content: { "application/json": { schema: { $ref: "#/components/schemas/Error" } } } } */
+  /* #swagger.responses[401] = { description: 'Not authenticated', content: { "application/json": { schema: { $ref: "#/components/schemas/Error" } } } } */
+  /* #swagger.responses[403] = { description: 'Admin role required', content: { "application/json": { schema: { $ref: "#/components/schemas/Error" } } } } */
+  adminOnly,
+  body('senderName').optional({ values: 'null' }).isString().trim().isLength({ max: 120 }),
+  body('enabled').optional().isBoolean(),
+  validate,
+  emailConfig.saveConfig,
+)
+adminRouter.get(
+  '/email/connect/start',
+  // #swagger.tags = ['Admin · Email']
+  // #swagger.summary = 'Begin the Gmail OAuth2 connect flow (admin only)'
+  // #swagger.description = 'Returns { url } to redirect the browser to Google. Reuses the google SSO OAuth client.'
+  // #swagger.security = [{ "cookieAuth": [] }, { "bearerAuth": [] }]
+  /* #swagger.responses[200] = { description: 'Authorization URL', content: { "application/json": { schema: { type: "object", properties: { url: { type: "string" } } } } } } */
+  /* #swagger.responses[400] = { description: 'Google OAuth client not configured', content: { "application/json": { schema: { $ref: "#/components/schemas/Error" } } } } */
+  /* #swagger.responses[401] = { description: 'Not authenticated', content: { "application/json": { schema: { $ref: "#/components/schemas/Error" } } } } */
+  /* #swagger.responses[403] = { description: 'Admin role required', content: { "application/json": { schema: { $ref: "#/components/schemas/Error" } } } } */
+  adminOnly,
+  emailConfig.connectStart,
+)
+adminRouter.get(
+  '/email/connect/callback',
+  // #swagger.tags = ['Admin · Email']
+  // #swagger.summary = 'OAuth2 callback — stores the refresh token, redirects to Settings'
+  // #swagger.security = [{ "cookieAuth": [] }, { "bearerAuth": [] }]
+  /* #swagger.responses[302] = { description: 'Redirect back to /admin/settings' } */
+  adminOnly,
+  emailConfig.connectCallback,
+)
+adminRouter.post(
+  '/email/test',
+  // #swagger.tags = ['Admin · Email']
+  // #swagger.summary = 'Send a test email (admin only)'
+  // #swagger.security = [{ "cookieAuth": [] }, { "bearerAuth": [] }]
+  /* #swagger.requestBody = { content: { "application/json": { schema: { type: "object", properties: { to: { type: "string", format: "email" } } } } } } */
+  /* #swagger.responses[200] = { description: 'Sent', content: { "application/json": { schema: { type: "object", properties: { sent: { type: "boolean" }, to: { type: "string" } } } } } } */
+  /* #swagger.responses[502] = { description: 'Send failed / not configured', content: { "application/json": { schema: { $ref: "#/components/schemas/Error" } } } } */
+  adminOnly,
+  body('to').optional({ values: 'falsy' }).isEmail().isLength({ max: 255 }),
+  validate,
+  emailConfig.testSend,
+)
+adminRouter.post(
+  '/email/disconnect',
+  // #swagger.tags = ['Admin · Email']
+  // #swagger.summary = 'Disconnect Gmail and disable email (admin only)'
+  // #swagger.security = [{ "cookieAuth": [] }, { "bearerAuth": [] }]
+  /* #swagger.responses[200] = { description: 'Disconnected config', content: { "application/json": { schema: { type: "object", additionalProperties: true } } } } */
+  /* #swagger.responses[401] = { description: 'Not authenticated', content: { "application/json": { schema: { $ref: "#/components/schemas/Error" } } } } */
+  /* #swagger.responses[403] = { description: 'Admin role required', content: { "application/json": { schema: { $ref: "#/components/schemas/Error" } } } } */
+  adminOnly,
+  emailConfig.disconnect,
+)
+
 // ── Authentication providers / SSO (admin only) ───────────────────────
 adminRouter.get(
   '/auth/providers',