feat(ui): inline conflict resolution with Keep This button

Replace the 'Go to Conflicts Page' link with inline conflict resolution.
Each conflict source now has a 'Keep This' button that resolves the
conflict directly from the book detail page.

- Conflict data now keyed by source name (koreader, web) instead of
  new/existing, with Source and Timestamp fields
- Display percentage scaled correctly (* 100)
- Fix page field name from current_page to page
- Add conflict resolution JavaScript in book-detail.ts
- Add 10-minute cooldown after resolution to prevent re-detection

web/src/book-detail.ts

@@ -104,6 +104,7 @@ interface MetadataEditorState {
   generateCover(): Promise<void>;
   removeCover(): void;
   saveMetadata(): Promise<void>;
+  resolveConflict(conflictId: string, winner: string): Promise<void>;
 }
 
 Alpine.data("bookDetail", () => {
@@ -149,6 +150,33 @@ Alpine.data("bookDetail", () => {
     hideProgressSyncModal,
     hideNotesModal,
 
+    async resolveConflict(conflictId: string, winner: string) {
+      try {
+        const resp = await fetch(`/api/conflicts/${conflictId}/resolve`, {
+          method: "POST",
+          headers: {
+            Authorization: getAuthHeader(),
+            "Content-Type": "application/json",
+          },
+          body: JSON.stringify({ winner }),
+        });
+
+        if (!resp.ok) {
+          const err = await resp.json().catch(() => ({}));
+          throw new Error(err.error || err.message || "Failed to resolve conflict");
+        }
+
+        hideProgressSyncModal();
+        showToast("Conflict resolved successfully", "success");
+        setTimeout(() => window.location.reload(), 500);
+      } catch (e) {
+        showToast(
+          e instanceof Error ? e.message : "Failed to resolve conflict",
+          "error",
+        );
+      }
+    },
+
     init() {
       const link = document.getElementById("back-link");
       if (!link) return;