fix: mobile viewport overflow — prevent horizontal clipping on iPhone

- Add overflow-x: hidden on html/body and max-width: 100vw
- Add overflow-x: hidden on root app container
- Add overflow-x: hidden on chat scroll container
- Make markdown tables scrollable with display: block + overflow-x: auto
- Add overflow-hidden + min-w-0 on expanded tool call content
- Fix tool result summary max-width from max-w-md to max-w-full

Fixes #26

src/index.css

@@ -6,11 +6,13 @@
   scrollbar-color: #52525b #27272a;
 }
 
-body {
+html, body {
   margin: 0;
   background: #1e1e24;
   color: #d4d4d8;
   font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
+  overflow-x: hidden;
+  max-width: 100vw;
 }
 
 @keyframes fade-in {
@@ -80,7 +82,7 @@ body {
 .markdown-body blockquote { border-left: 3px solid rgba(34,211,238,0.4); padding-left: 12px; margin: 8px 0; opacity: 0.8; }
 .markdown-body h1, .markdown-body h2, .markdown-body h3 { margin: 12px 0 4px; }
 .markdown-body a { color: #67e8f9; text-decoration: underline; }
-.markdown-body table { border-collapse: collapse; margin: 8px 0; }
+.markdown-body table { border-collapse: collapse; margin: 8px 0; display: block; overflow-x: auto; max-width: 100%; }
 .markdown-body th, .markdown-body td { border: 1px solid rgba(255,255,255,0.08); padding: 6px 12px; }
 .markdown-body th { background: rgba(255,255,255,0.04); }
 .markdown-body img { max-width: 100%; border-radius: 8px; }