feat: add manual SD card data upload for offline NRLs; rename RecordingSession to MonitoringSession

- Add POST /api/projects/{project_id}/nrl/{location_id}/upload-data endpoint
  accepting a ZIP or multi-file select of .rnd/.rnh files from an SD card.
  Parses .rnh metadata for session start/stop times, serial number, and store
  name. Creates a MonitoringSession (no unit assignment required) and DataFile
  records for each measurement file.

- Add Upload Data button and collapsible upload panel to the NRL detail Data
  Files tab, with inline success/error feedback and automatic file list refresh
  via HTMX after import.

- Rename RecordingSession -> MonitoringSession throughout the codebase
  (models.py, projects.py, project_locations.py, scheduler.py, roster_rename.py,
  main.py, init_projects_db.py, scripts/rename_unit.py). DB table renamed from
  recording_sessions to monitoring_sessions; old indexes dropped and recreated.

- Update all template UI copy from Recording Sessions to Monitoring Sessions
  (nrl_detail, projects/detail, session_list, schedule_oneoff, roster).

- Add backend/migrate_rename_recording_to_monitoring_sessions.py for applying
  the table rename on production databases before deploying this build.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

templates/projects/overview.html

@@ -78,9 +78,16 @@
 <!-- Create Project Modal -->
 <div id="createProjectModal" class="hidden fixed inset-0 bg-black bg-opacity-50 z-50 flex items-center justify-center">
     <div class="bg-white dark:bg-slate-800 rounded-xl shadow-2xl w-full max-w-4xl max-h-[90vh] overflow-y-auto">
-        <div class="p-6 border-b border-gray-200 dark:border-gray-700">
-            <h2 class="text-2xl font-bold text-gray-900 dark:text-white">Create New Project</h2>
-            <p class="text-gray-600 dark:text-gray-400 mt-1">Select a project type and configure settings</p>
+        <div class="p-6 border-b border-gray-200 dark:border-gray-700 flex items-start justify-between">
+            <div>
+                <h2 class="text-2xl font-bold text-gray-900 dark:text-white">Create New Project</h2>
+                <p class="text-gray-600 dark:text-gray-400 mt-1">Select a project type and configure settings</p>
+            </div>
+            <button onclick="hideCreateProjectModal()" class="text-gray-400 hover:text-gray-600 dark:hover:text-gray-200 ml-4">
+                <svg class="w-6 h-6" fill="none" stroke="currentColor" viewBox="0 0 24 24">
+                    <path stroke-linecap="round" stroke-linejoin="round" stroke-width="2" d="M6 18L18 6M6 6l12 12"></path>
+                </svg>
+            </button>
         </div>
 
         <div class="p-6" id="createProjectContent">
@@ -97,6 +104,12 @@
                     <div class="animate-pulse bg-gray-200 dark:bg-gray-700 h-48 rounded-lg"></div>
                     <div class="animate-pulse bg-gray-200 dark:bg-gray-700 h-48 rounded-lg"></div>
                 </div>
+                <div class="mt-6 flex justify-end">
+                    <button type="button" onclick="hideCreateProjectModal()"
+                            class="px-6 py-2 border border-gray-300 dark:border-gray-600 rounded-lg text-gray-700 dark:text-gray-300 hover:bg-gray-50 dark:hover:bg-gray-700">
+                        Cancel
+                    </button>
+                </div>
             </div>
 
             <!-- Step 2: Project Details Form (hidden initially) -->