Make photo upload limit configurable via admin settings (#40)

backend/migrations/core/045_add_max_files_per_upload_setting.js

@@ -0,0 +1,48 @@
+const { DEFAULT_MAX_FILES_PER_UPLOAD, MAX_ALLOWED_FILES_PER_UPLOAD } = require('../../src/services/uploadSettings');
+
+exports.up = async function up(knex) {
+  const settingKey = 'general_max_files_per_upload';
+
+  const existing = await knex('app_settings')
+    .where({ setting_key: settingKey })
+    .first();
+
+  if (existing) {
+    // Normalize existing value into allowed bounds
+    let parsedValue;
+    try {
+      parsedValue = existing.setting_value != null ? JSON.parse(existing.setting_value) : null;
+    } catch {
+      parsedValue = existing.setting_value;
+    }
+
+    const numeric = Number(parsedValue);
+    let normalized = DEFAULT_MAX_FILES_PER_UPLOAD;
+    if (Number.isFinite(numeric) && numeric >= 1) {
+      normalized = Math.min(MAX_ALLOWED_FILES_PER_UPLOAD, Math.floor(numeric));
+    }
+
+    if (normalized !== numeric) {
+      await knex('app_settings')
+        .where({ setting_key: settingKey })
+        .update({
+          setting_value: JSON.stringify(normalized),
+          updated_at: new Date()
+        });
+    }
+    return;
+  }
+
+  await knex('app_settings').insert({
+    setting_key: settingKey,
+    setting_value: JSON.stringify(DEFAULT_MAX_FILES_PER_UPLOAD),
+    setting_type: 'general',
+    updated_at: new Date()
+  });
+};
+
+exports.down = async function down(knex) {
+  await knex('app_settings')
+    .where({ setting_key: 'general_max_files_per_upload' })
+    .del();
+};