fix: move copy code button to bottom-right and increase modal width

- Move copy code button from bottom-left to bottom-right of code blocks
- Increase main modal width from 70vw to 80vw
- Increase max-width from 800px to 1000px
- Prevents horizontal scrolling in chat area
- Applied to both builtin and PicoCSS override styles

src/uncloseai-modal-builtin.css

@@ -9,8 +9,8 @@ dialog#uncloseai-embedded-modal {
   z-index: 2000;
   
   /* Desktop centered */
-  width: 70vw;
-  max-width: 800px;
+  width: 80vw;
+  max-width: 1000px;
   height: 90vh;
   top: 50%;
   left: 50%;
@@ -801,7 +801,7 @@ dialog#tts-modal {
 .uncloseai-code-copy-btn {
   position: absolute;
   bottom: 8px;
-  left: 8px;
+  right: 8px;
   background: rgba(0, 0, 0, 0.9);
   color: white;
   border: none;

src/uncloseai-modal-pico.css

@@ -17,8 +17,8 @@ dialog#uncloseai-embedded-modal[data-theme] {
   transform: translate(-50%, -50%) !important;
   
   /* Override PicoCSS sizing that sets min-width:100%, min-height:100% */
-  width: 70vw !important;
-  max-width: 800px !important;
+  width: 80vw !important;
+  max-width: 1000px !important;
   height: 90vh !important;
   min-width: auto !important;
   min-height: auto !important;
@@ -857,7 +857,7 @@ dialog#tts-modal::backdrop {
 .uncloseai-code-copy-btn {
   position: absolute;
   bottom: 8px;
-  left: 8px;
+  right: 8px;
   background: rgba(0, 0, 0, 0.9);
   color: white;
   border: none;