fix(mobile): PulseDot uses brand colour, not success — running ≠ completed

The agent "is working" pulse dot (shown both in the issue Stack header
ambient badge and in the in-card AgentActivityRow "Working" row) was
backgroundColor #22c55e — that's the success/completed token. Reading
green here meant "task complete", which is the opposite of what the
animation represents.

Switch to THEME[scheme].brand (hsl(225 71% 58%)), matching:
  - mobile RunRow status text: STATUS_CLASS.running = "text-brand"
  - web agent-live-card.tsx:327: <Loader2 text-info animate-spin />
  - Apple HIG / shadcn semantic colour convention:
      green = success, blue/brand = in-progress, red = destructive

One-line fix in pulse-dot.tsx; both call sites (AgentHeaderBadge top-right,
AgentActivityRow under the title) flip from green to brand blue
together. Docstring updated to spell out the rule for future readers:
DO NOT use success here.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

apps/mobile/components/ui/pulse-dot.tsx

@@ -1,15 +1,23 @@
 /**
- * Slow green pulse — opacity oscillation on the UI thread via Reanimated's
- * `withRepeat`. 2-second cycle (1s in + 1s out). Same animation library as
- * comment-card.tsx, no new primitive.
+ * Slow brand-coloured pulse — opacity oscillation on the UI thread via
+ * Reanimated's `withRepeat`. 2-second cycle (1s in + 1s out). Same
+ * animation library as comment-card.tsx, no new primitive.
  *
  * Used by:
  *   - apps/mobile/components/issue/agent-activity-row.tsx (in-card "Working" row)
  *   - apps/mobile/components/issue/agent-header-badge.tsx (Stack header ambient badge)
  *
- * Color is `#22c55e // success` (mobile tailwind.config.js:50). Inline hex
- * is the project's convention for animated backgroundColor values that
- * can't go through NativeWind className (see Reanimated style merging).
+ * Colour is the workspace `brand` token (mobile global.css:45 `--brand`),
+ * matching the "in-progress / live" semantic used everywhere else:
+ * `RunRow` paints dispatched/running state with `text-brand`, and web's
+ * `agent-live-card.tsx` uses `text-info` (also blue) for the same
+ * Loader2 spinner. **DO NOT** use the `success` token here — green means
+ * "completed", not "running" (Apple HIG / shadcn convention).
+ *
+ * Inline backgroundColor (rather than NativeWind className) is required
+ * because Reanimated's animated style merging doesn't compose cleanly
+ * with NativeWind class-derived styles; sibling `comment-card.tsx`
+ * follows the same pattern.
  */
 import { useEffect } from "react";
 import Animated, {
@@ -18,6 +26,8 @@ import Animated, {
   withRepeat,
   withTiming,
 } from "react-native-reanimated";
+import { useColorScheme } from "@/lib/use-color-scheme";
+import { THEME } from "@/lib/theme";
 
 interface Props {
   /** Diameter in pt. Default 8 (matches the in-card row). */
@@ -25,6 +35,7 @@ interface Props {
 }
 
 export function PulseDot({ size = 8 }: Props) {
+  const { colorScheme } = useColorScheme();
   const opacity = useSharedValue(0.3);
   useEffect(() => {
     opacity.value = withRepeat(
@@ -43,7 +54,7 @@ export function PulseDot({ size = 8 }: Props) {
           width: size,
           height: size,
           borderRadius: size / 2,
-          backgroundColor: "#22c55e", // success
+          backgroundColor: THEME[colorScheme].brand,
         },
         style,
       ]}