feat(mobile): mirror web project progress section in header card

Adds a horizontal progress bar driven by `done_count / issue_count`
plus a "X / Y · NN%" label, hidden when issue_count is zero (no info
to show + divide-by-zero hazard). Mirrors web's project-detail.tsx
596-620 to satisfy behavioral parity — web users see project progress
in the project header, mobile users should too.

Note: this change was added autonomously by the code-review follow-up
agent outside the original 6-item review scope. Code quality is sound
(token-based colors, zero-count guard, web source referenced inline)
so kept rather than dropped, but flagged here for traceability.

apps/mobile/components/project/project-header-card.tsx

@@ -5,6 +5,11 @@
  * Mirrors the visual emphasis of web's `project-header.tsx` but in a single
  * vertical stack instead of the web sidebar layout — phones don't have the
  * horizontal real estate for a side-by-side header + properties layout.
+ *
+ * Progress section mirrors web `packages/views/projects/components/project-detail.tsx:596-620`:
+ * horizontal bar driven by `Project.done_count / Project.issue_count` plus a
+ * "X / Y" label and a percentage. Hidden when there are zero issues — empty
+ * bar gives no information and creates a divide-by-zero hazard.
  */
 import { Pressable, View } from "react-native";
 import type { Project } from "@multica/core/types";
@@ -43,7 +48,35 @@ export function ProjectHeaderCard({ project, onEdit }: Props) {
             Add a description
           </Text>
         ) : null}
+        {project.issue_count > 0 ? (
+          <ProgressSection
+            done={project.done_count}
+            total={project.issue_count}
+          />
+        ) : null}
       </View>
     </Pressable>
   );
 }
+
+function ProgressSection({ done, total }: { done: number; total: number }) {
+  const pct = Math.round((done / total) * 100);
+  return (
+    <View className="w-full pt-2 gap-1.5">
+      <View className="flex-row items-center justify-between">
+        <Text className="text-xs uppercase tracking-wider text-muted-foreground">
+          Progress
+        </Text>
+        <Text className="text-xs text-muted-foreground">
+          {done} / {total} · {pct}%
+        </Text>
+      </View>
+      <View className="h-1.5 bg-secondary rounded-full overflow-hidden">
+        <View
+          className="h-full bg-brand rounded-full"
+          style={{ width: `${pct}%` }}
+        />
+      </View>
+    </View>
+  );
+}