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/css/base.css

@@ -1225,3 +1225,31 @@ body:has(.page-messages) {
     color: var(--text-muted);
     text-decoration: underline;
 }
+
+.response-time-indicator {
+    position: fixed;
+    left: 0.5rem;
+    bottom: 0.5rem;
+    z-index: 50;
+    padding: 0.15rem 0.45rem;
+    font-family: var(--font-mono);
+    font-size: 0.6875rem;
+    line-height: 1;
+    color: var(--text-muted);
+    background: var(--bg-card);
+    border: 1px solid var(--border);
+    border-radius: var(--radius-input);
+    opacity: 0.55;
+    pointer-events: none;
+    user-select: none;
+}
+
+.response-time-indicator:hover {
+    opacity: 0.9;
+}
+
+@media (max-width: 768px) {
+    .response-time-indicator {
+        display: none;
+    }
+}

devplacepy/static/css/components.css

@@ -133,6 +133,10 @@ dp-content {
     display: block;
 }
 
+dp-title {
+    display: inline;
+}
+
 dp-upload {
     display: block;
 }

devplacepy/static/css/docs.css

@@ -550,29 +550,8 @@ pre.code-pre > .code-gutter {
     font-variant-numeric: tabular-nums;
 }
 
-pre.code-has-copy {
-    position: relative;
-}
-
-pre.code-has-copy > .code-copy-btn {
-    position: absolute;
-    top: 0.4rem;
-    right: 0.4rem;
-    z-index: 1;
-    padding: 0.2rem 0.6rem;
-    font-size: 0.7rem;
-    color: var(--text-secondary);
-    background: rgba(40, 44, 52, 0.9);
-    border: 1px solid rgba(255, 255, 255, 0.14);
-    border-radius: var(--radius);
-    cursor: pointer;
-    opacity: 1;
-}
-
-pre.code-has-copy > .code-copy-btn:hover {
-    color: var(--white);
-    border-color: var(--accent, #6366f1);
-}
+/* The generic `pre.code-has-copy` copy-button styles moved to markdown.css so they
+   apply to backend-rendered content everywhere, not only on docs pages. */
 
 /* ---- Docs search ---- */
 .docs-search-form {

devplacepy/static/css/markdown.css

@@ -150,6 +150,30 @@ dp-content:hover .content-copy-btn,
     border-color: var(--accent);
 }
 
+pre.code-has-copy {
+    position: relative;
+}
+
+pre.code-has-copy > .code-copy-btn {
+    position: absolute;
+    top: 0.4rem;
+    right: 0.4rem;
+    z-index: 1;
+    padding: 0.2rem 0.6rem;
+    font-size: 0.7rem;
+    color: var(--text-secondary);
+    background: rgba(40, 44, 52, 0.9);
+    border: 1px solid rgba(255, 255, 255, 0.14);
+    border-radius: var(--radius);
+    cursor: pointer;
+    opacity: 1;
+}
+
+pre.code-has-copy > .code-copy-btn:hover {
+    color: var(--white);
+    border-color: var(--accent, #6366f1);
+}
+
 .embed-youtube {
     position: relative;
     width: 100%;