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>

backend/templates_config.py

@@ -73,10 +73,16 @@ def jinja_log_tail_display(s):
         return str(s)
 
 
+def jinja_local_datetime_input(dt):
+    """Jinja filter: format UTC datetime as local YYYY-MM-DDTHH:MM for <input type='datetime-local'>."""
+    return format_local_datetime(dt, "%Y-%m-%dT%H:%M")
+
+
 # Register Jinja filters and globals
 templates.env.filters["local_datetime"] = jinja_local_datetime
 templates.env.filters["local_time"] = jinja_local_time
 templates.env.filters["local_date"] = jinja_local_date
+templates.env.filters["local_datetime_input"] = jinja_local_datetime_input
 templates.env.filters["fromjson"] = jinja_fromjson
 templates.env.globals["timezone_abbr"] = jinja_timezone_abbr
 templates.env.globals["get_user_timezone"] = get_user_timezone