refactor: restyle prompt input via tokens

src/index.css

@@ -547,116 +547,7 @@ body {
   }
 }
 
-.prompt-input-container {
-  display: flex;
-  flex-direction: column;
-  border-top: 1px solid var(--border-base);
-  background-color: var(--surface-base);
-}
 
-.prompt-input-wrapper {
-  display: flex;
-  align-items: flex-end;
-  gap: 8px;
-  padding: 12px 16px;
-}
-
-.prompt-input {
-  flex: 1;
-  min-height: 40px;
-  max-height: 200px;
-  padding: 10px 12px;
-  border: 1px solid var(--border-base);
-  border-radius: 6px;
-  font-family: inherit;
-  font-size: 14px;
-  line-height: 1.5;
-  resize: none;
-  background-color: var(--surface-base);
-  color: inherit;
-  outline: none;
-  transition: border-color 150ms ease;
-}
-
-.prompt-input:focus {
-  border-color: var(--accent-primary);
-}
-
-.prompt-input:disabled {
-  opacity: 0.6;
-  cursor: not-allowed;
-}
-
-.prompt-input::placeholder {
-  color: var(--text-muted);
-}
-
-.send-button {
-  width: 40px;
-  height: 40px;
-  border-radius: 6px;
-  background-color: var(--accent-primary);
-  color: white;
-  border: none;
-  cursor: pointer;
-  display: flex;
-  align-items: center;
-  justify-content: center;
-  transition:
-    opacity 150ms ease,
-    transform 150ms ease;
-  flex-shrink: 0;
-}
-
-.send-button:hover:not(:disabled) {
-  opacity: 0.9;
-  transform: scale(1.05);
-}
-
-.send-button:active:not(:disabled) {
-  transform: scale(0.95);
-}
-
-.send-button:disabled {
-  opacity: 0.4;
-  cursor: not-allowed;
-}
-
-.send-icon {
-  font-size: 16px;
-}
-
-.spinner-small {
-  width: 16px;
-  height: 16px;
-  border: 2px solid rgba(255, 255, 255, 0.3);
-  border-top-color: white;
-  border-radius: 50%;
-  animation: spin 1s linear infinite;
-}
-
-.prompt-input-hints {
-  padding: 0 16px 8px 16px;
-  display: flex;
-  justify-content: space-between;
-  align-items: center;
-}
-
-.hint {
-  font-size: 12px;
-  color: var(--text-muted);
-}
-
-.hint kbd {
-  display: inline-block;
-  padding: 2px 6px;
-  font-size: 11px;
-  font-family: monospace;
-  background-color: var(--surface-secondary);
-  border: 1px solid var(--border-base);
-  border-radius: 3px;
-  margin: 0 2px;
-}
 
 .session-view {
   display: flex;