feat(inspector): improve session UI, skills dropdown, and visual polish (#179)

- Add delete button on ended sessions (visible on hover)
- Darken ended sessions with opacity and "ended" pill badge
- Sort ended sessions to bottom of list
- Add token usage pill in chat header
- Disable input when session ended
- Add Official Skills dropdown with SDK and Rivet presets
- Format session IDs shorter with full ID on hover
- Add arrow icon to "Configure persistence" link
- Add agent logo SVGs

frontend/packages/inspector/src/utils/format.ts

@@ -16,3 +16,9 @@ export const formatTime = (value: string) => {
 };
 
 export const escapeSingleQuotes = (value: string) => value.replace(/'/g, `'\\''`);
+
+export const formatShortId = (value: string, head = 8, tail = 4) => {
+  if (!value) return "";
+  if (value.length <= head + tail + 1) return value;
+  return `${value.slice(0, head)}...${value.slice(-tail)}`;
+};