Add PDCalendar component

[davidnmbond]

Summary

Adds PDCalendar<TItem>, a generic calendar for anything with a start and an end in time. It reads items through selector delegates, so any type can be shown without converting it to a calendar model.

• Views: a Month grid, a Week time grid (seven day columns against an hour axis) and an Agenda list for narrow screens.
• Toolbar: previous, next, today, a title ("October 2026", "12 to 18 Oct 2026") and a view switcher, built from Bootstrap button groups; every part can be hidden.
• Time zones: TimeZone (default TimeZoneInfo.Local) decides which day and hour an item falls in. The week view's hour axis is real elapsed time, so the day the clocks go forward shows 23 hours and the day they go back shows 25, with the repeated hour labelled by its UTC offsets. Items spanning midnight are split across day columns.
• Layout: overlapping items in the week view sit side by side (greedy column packing, with a shared column count across a chain of overlaps). The month view lists up to MaxItemsPerDay items per day with a "+n more" button that opens that day's agenda, and shows multi-day items on every day.
• Lazy loading: OnVisibleRangeChanged is raised whenever the visible range changes, including on first show; IsLoading shows the library's PDBusyOverlay.
• Accessibility: ARIA grid roles with the focused day or hour as the active descendant. Arrow keys move, Enter or Space selects, Page Up and Page Down change period, and Home goes to today. Items are buttons. Transitions respect prefers-reduced-motion, and below 576 px the month view collapses items to dots.
• No JavaScript unless ScrollToHour is set; that uses the existing setProperty helper in common.js.

Public API

• PDCalendar<TItem> parameters:
  • Data: Items, StartSelector, EndSelector, TitleSelector, KeySelector, CssClassSelector, TooltipSelector, IsDisabledSelector, ItemTemplate, TimeZone, Clock (TimeProvider).
  • State: Date/DateChanged (DateOnly?, null means today), View/ViewChanged, AvailableViews, SelectedItem/SelectedItemChanged, FirstDayOfWeek (default Monday), MinDate, MaxDate, IsLoading.
  • Events: OnItemSelected, OnItemDoubleClick, OnSlotSelected (DateTimeOffset), OnVisibleRangeChanged ((DateTimeOffset From, DateTimeOffset To)).
  • Layout: FirstVisibleHour, LastVisibleHour, SlotHeight, MinItemHeight, ScrollHeight, ScrollToHour, MaxItemsPerDay, AgendaDays, NowIndicator, ShadeWeekends, WeekendDays, DayCssClassSelector, TimeFormat, ShowToolbar, ShowNavigation, ShowToday, ShowTitle, ShowViewSwitcher, EmptyText, AriaLabel, CssClass.
• Methods: NavigateAsync, GoToTodayAsync, GoToDateAsync, SetViewAsync, ShowDayAgendaAsync, CanNavigate. Read-only properties: Id, CurrentDate, CurrentView, CurrentSelection, VisibleRange, Title.
• New enum: CalendarView (Month, Week, Agenda).
• New public static helpers, each usable and testable without a renderer: CalendarMath (visible dates and ranges, navigation, start and length of a day, wall clock to instant with gap and overlap handling, titles), CalendarLayoutEngine (SplitByDay, PackColumns).
• New models: CalendarTimeAxis, CalendarAxisRow, CalendarHourSlot, CalendarSegment<TItem>.

No existing public member is changed or removed.

Tests and coverage

• 126 new tests: 71 plain unit tests for the helpers and 55 bUnit tests for the component. They cover month and week range maths with each first day of week, the Europe/London spring and autumn changes, a custom zone where midnight is skipped and one where it is repeated, items spanning midnight and days, overlap packing with one, two, three and chained overlaps, selection, keyboard handling, view switching, OnVisibleRangeChanged, MinDate and MaxDate, ItemTemplate, "+n more", the empty state, time zone changes, the current time indicator driven by a test TimeProvider, ScrollToHour and disposal.
• Full suite: 3,927 tests, 0 failed, 0 skipped.
• Coverage of the new library files with the repo's coverage.config: 576 of 576 lines (100%) and 299 of 300 branches. Because that config leaves out [CompilerGenerated] code, and so async method bodies and Razor lambdas, I also measured with that exclusion removed: 913 of 916 lines (99.7%) and 457 of 474 branches (96.4%). The three lines not covered are the ObjectDisposedException guard in the minute timer callback, which only runs if a tick races the renderer's disposal.

Command used:

dotnet test PanoramicData.Blazor.Test/PanoramicData.Blazor.Test.csproj -- --coverage --coverage-output-format cobertura --coverage-settings coverage.config --results-directory <dir> --coverage-output result.cobertura.xml

Demo

A new /pdcalendar page (Demo | Source | Documentation) shows a two-station radio schedule in Europe/London, loaded lazily with a deliberate delay so the busy overlay shows. It has overlapping shows, a late show running past midnight, a festival spanning a weekend, a button to show the week the clocks go back (25 October 2026), controls for most parameters, and a second agenda-only calendar showing ItemTemplate and disabled items. Also added to the NavMenu. ComponentDocumentation.md is regenerated with GenerateDocs.ps1. The hand-written PDChat notes that the script would have dropped are kept, and one generated PDTree line is left out because its source XML summary contains em dashes.

I checked the page by running the Web host and driving it with headless Chromium (Playwright). I confirmed the week, clock-change week, month, "+n more" to agenda, phone-width (no horizontal scroll) and Documentation views, keyboard focus movement and item selection. The only console errors were the existing BlazorMonaco "monaco is undefined" messages, which also appear on other documentation tabs such as /pdbutton?tab=docs. I did not test with a screen reader or on a real phone.

dotnet build PanoramicData.Blazor.slnx gives 0 errors. The 2 warnings are the existing "packaging has been disabled" messages from the Web and WebAssembly.Server hosts.

🤖 Generated with Claude Code

[codacy-production]

Up to standards ✅

🟢 Issues 0 issues

Results:
0 new issues

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🟢 Metrics 374 complexity · 2 duplication

Metric	Results
Complexity	374
Duplication	2

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🟢 Coverage 100.00% diff coverage · +0.01% coverage variation

Metric	Results
Coverage variation	✅ +0.01% coverage variation
Diff coverage	✅ 100.00% diff coverage

View coverage diff in Codacy

Coverage variation details

	Coverable lines	Covered lines	Coverage
Common ancestor commit (1b4b7bc)	16056	16033	99.86%
Head commit (da89ab9)	16679 (+623)	16656 (+623)	99.86% (+0.01%)

Coverage variation is the difference between the coverage for the head and common ancestor commits of the pull request branch: <coverage of head commit> - <coverage of common ancestor commit>

Diff coverage details

	Coverable lines	Covered lines	Diff coverage
Pull request (#244)	623	623	100.00%

Diff coverage is the percentage of lines that are covered by tests out of the coverable lines that the pull request added or modified: <covered lines added or modified>/<coverable lines added or modified> * 100%

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