Refactor monster_catches from table to view and add overwrite option

- Convert monster_catches from table to view for automatic calculation
- Add overwrite checkbox to monster import UI
- Remove manual INSERT/UPDATE logic for catches (now handled by view)
- Simplify API endpoints to query view instead of managing state
- Add confirmation dialog for overwrite operation

Benefits:
- No data duplication
- Always accurate catch status based on current steps
- Simpler codebase with less state management
- Easier to reset steps without orphaned catch records

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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

public/app.js

@@ -823,6 +823,7 @@ function renderMonsterTimeline(timeline) {
 // Monster CSV Import
 async function importMonsters() {
   const fileInput = document.getElementById('monster-csv-file');
+  const overwriteCheckbox = document.getElementById('monster-overwrite');
   const messageDiv = document.getElementById('monster-import-message');
 
   if (!fileInput.files || !fileInput.files[0]) {
@@ -830,6 +831,19 @@ async function importMonsters() {
     return;
   }
 
+  const overwrite = overwriteCheckbox.checked;
+
+  // Confirm if overwrite is selected
+  if (overwrite) {
+    const confirmed = confirm(
+      'WARNING: This will DELETE all existing monsters and monster catches!\n\n' +
+      'Are you sure you want to proceed?'
+    );
+    if (!confirmed) {
+      return;
+    }
+  }
+
   const file = fileInput.files[0];
   const reader = new FileReader();
 
@@ -846,18 +860,22 @@ async function importMonsters() {
         return { date, monster_name, monster_description, step_goal, monster_icon };
       });
 
-      const result = await apiCall('/api/monsters/import', 'POST', { data });
+      const result = await apiCall('/api/monsters/import', 'POST', { data, overwrite });
 
-      showMessage(
-        messageDiv,
-        `Success! Created ${result.monstersCreated} monsters, updated ${result.monstersUpdated}`,
-        'success'
-      );
+      let successMessage;
+      if (overwrite) {
+        successMessage = `Success! Deleted ${result.monstersDeleted} old monsters, created ${result.monstersCreated} new monsters`;
+      } else {
+        successMessage = `Success! Created ${result.monstersCreated} monsters, updated ${result.monstersUpdated}`;
+      }
+
+      showMessage(messageDiv, successMessage, 'success');
 
       // Reload monsters
       await loadDailyMonsters();
 
       fileInput.value = '';
+      overwriteCheckbox.checked = false;
     } catch (error) {
       showMessage(messageDiv, `Error: ${error.message}`, 'error');
     }