docs: document server-side rendering pipeline, response timing middleware, and Telegram pairing API

- Add comprehensive documentation for backend content rendering in AGENTS.md, detailing the new `render_content` and `render_title` Jinja globals built on mistune with media processing, emoji shortcodes, and XSS protection
- Document the `X-Response-Time` header and bottom-left render time indicator in README.md
- Update bot token pricing documentation to clarify fallback vs gateway cost headers
- Add `email_accounts` to soft-delete tables and `idx_users_role` composite index in database schema
- Implement `telegram_pairings` and `telegram_links` table creation with column migration and indexes
- Add `/profile/{username}/telegram` endpoint to docs API with request/unpair actions
- Register `TelegramService` in main.py lifespan and add `response_timing` middleware emitting `X-Response-Time` header
- Introduce `TelegramPairForm` model and `guard_public_host_sync` synchronous host validation function

devplacepy/static/js/Application.js

@@ -22,6 +22,7 @@ import { CustomizationToggle } from "./CustomizationToggle.js";
 import { NotificationPrefs } from "./NotificationPrefs.js";
 import { AiCorrection } from "./AiCorrection.js";
 import { AiModifier } from "./AiModifier.js";
+import { TelegramPairing } from "./TelegramPairing.js";
 import { AdminNotificationDefaults } from "./AdminNotificationDefaults.js";
 import { UserAiUsage } from "./UserAiUsage.js";
 import { Tabs } from "./Tabs.js";
@@ -66,6 +67,7 @@ class Application {
         this.notificationPrefs = new NotificationPrefs();
         this.aiCorrection = new AiCorrection();
         this.aiModifier = new AiModifier();
+        this.telegramPairing = new TelegramPairing();
         this.adminNotificationDefaults = new AdminNotificationDefaults();
         this.userAiUsage = new UserAiUsage();
         this.tabs = new Tabs();