feat: monitoring session improvements — UTC fix, period hours, calendar, session detail

- Fix UTC display bug: upload_nrl_data now wraps RNH datetimes with
  local_to_utc() before storing, matching patch_session behavior.
  Period type and label are derived from local time before conversion.

- Add period_start_hour / period_end_hour to MonitoringSession model
  (nullable integers 0–23). Migration: migrate_add_session_period_hours.py

- Update patch_session to accept and store period_start_hour / period_end_hour.
  Response now includes both fields.

- Update get_project_sessions to compute "Effective: M/D H:MM AM → M/D H:MM AM"
  string from period hours and pass it to session_list.html.

- Rework period edit UI in session_list.html: clicking the period badge now
  opens an inline editor with period type selector + start/end hour inputs.
  Selecting a period type pre-fills default hours (Day: 7–19, Night: 19–7).

- Wire period hours into _build_location_data_from_sessions: uses
  period_start/end_hour when set, falls back to hardcoded defaults.

- RND viewer: inject SESSION_PERIOD_START/END_HOUR from template context.
  renderTable() dims rows outside the period window (opacity-40) with a
  tooltip; shows "(N in period window)" in the row count.

- New session detail page at /api/projects/{id}/sessions/{id}/detail:
  shows breadcrumb, files list with View/Download/Report actions,
  editable session info form (label, period type, hours, times).

- Add local_datetime_input Jinja filter for datetime-local input values.

- Monthly calendar view: new get_sessions_calendar endpoint returns
  sessions_calendar.html partial; added below sessions list in detail.html.
  Color-coded per NRL with legend, HTMX prev/next navigation, session dots
  link to detail page.

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

templates/projects/detail.html

@@ -208,6 +208,19 @@
                 <div class="text-center py-8 text-gray-500">Loading sessions...</div>
             </div>
         </div>
+
+        <!-- Monthly Calendar -->
+        <div class="mt-6 bg-white dark:bg-slate-800 rounded-xl shadow-lg p-6">
+            <div class="flex items-center justify-between mb-4">
+                <h3 class="text-lg font-semibold text-gray-900 dark:text-white">Calendar View</h3>
+            </div>
+            <div id="sessions-calendar"
+                 hx-get="/api/projects/{{ project_id }}/sessions-calendar"
+                 hx-trigger="load"
+                 hx-swap="innerHTML">
+                <div class="text-center py-6 text-gray-400 text-sm">Loading calendar…</div>
+            </div>
+        </div>
     </div>
 
     <!-- Data Files Tab -->