fix(frontend): issues from the 10-25 Chrome sweep

- Incident detail "← Incidents" used router.back(), so arriving from Live
  or a shared link it went to the map / out of the app. Now a Link.
- Resolved incidents showed "0m elapsed" (manual resolve sets no
  resolved_at, updated_at can predate the last call): end is now the
  latest of resolved_at, updated_at and the newest call.
- Admin: the max-width toggle wrapped the tab bar, so it reflowed on every
  tab switch and left the cursor over e.g. "Close calls". Body only now.
- STT Eval sat on "Loading…" forever when a scanned page had zero matches
  but a next_cursor — the refill effect didn't depend on cursor.
- Trip event blocks used dark-only bg-indigo-950/60: unreadable in light
  mode. Theme tokens now.
- Reassign modal said "connected for the first time" on configured nodes.
- Dark-mode placeholders dimmed + italic; they read as filled-in values.

Frontend unverified locally (no Node, #207); CI build typechecks.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

drb-frontend/app/trips/[id]/page.tsx

@@ -484,15 +484,17 @@ function DayTimeline({
                   style={{ top, height, left: 60, right: 0 }}
                   className={`absolute rounded-lg px-3 py-2 overflow-hidden group transition-colors z-20 ${
                     isConflict
-                      ? "bg-red-950/70 border border-red-700/70"
-                      : "bg-indigo-950/60 border border-indigo-800/50 hover:border-indigo-600/70"
+                      // Theme tokens: the old bg-indigo-950/60 had no light-mode
+                      // override, so light mode got dark text on a dark block.
+                      ? "bg-sev-major/15 border border-sev-major/50"
+                      : "bg-accent/15 border border-accent/40 hover:border-accent/70"
                   }`}
                 >
                   <div className="flex items-start justify-between gap-2 h-full">
                     <div className="min-w-0 flex-1">
                       <p className="text-white text-xs font-semibold leading-tight truncate">{e.title}</p>
                       {height >= 44 && (
-                        <p className={`text-xs font-mono mt-0.5 ${isConflict ? "text-red-400" : "text-indigo-400"}`}>
+                        <p className={`text-xs font-mono mt-0.5 ${isConflict ? "text-sev-major" : "text-accent"}`}>
                           {fmtTime(e.start_time)}
                           {e.end_time ? ` – ${fmtTime(e.end_time)}` : ""}
                           {isConflict ? "  ⚠ conflict" : ""}