revert(widget): leave the month grid responsive, as it always was (#103)

The month widget's columns were never the problem. MonthWidget.kt has divided
the width it is given by seven since v2.5.0 and 2.16.0 did not touch that line
— only the title formatter. What 2.16.0 did change was AgendaWidget, which
gained SizeMode.Exact and became structurally identical to MonthWidget, so R8
merged the two classes and collapsed Glance's provider map. That is #89, and it
is what handed the month grid the wrong widget's measurements.

The keep rule from #89 is the fix. Reverting the fixed-size grid, its metrics
table and the raised minResizeWidth. The size setting stays, agenda-only, which
is all #51 ever asked for.

CHANGELOG.md

@@ -28,11 +28,10 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - The calendar picker in the event form and in the .ics import screen now ends
   with a **"Missing a calendar?"** row that opens Settings → Calendars, where
   those marks then explain why a calendar isn't offered ([#76]).
-- Both home-screen widgets have a size you set yourself. **Settings → Widgets →
-  Widget size** offers Small, Medium, Large and Extra large: it sets how big the
-  agenda widget's text is, and how big the month widget's day columns and text
-  are. Small is what the widgets look like today, so nothing changes until you
-  turn it up ([#51], [#103]).
+- The agenda widget's text size is yours to set. **Settings → Agenda → Agenda
+  widget size** offers Small, Medium, Large and Extra large, replacing the guess
+  the widget used to make from its own measurements. Small is what it looks like
+  today, so nothing changes until you turn it up ([#51]).
 
 ### Changed
 - Calendula's source code now lives on **Codeberg**, where its issues already
@@ -42,19 +41,13 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
   unaffected.
 
 ### Fixed
-- The month widget shows all seven days again. Unless it happened to be resized
-  to just the right shape, it drew only about four columns and cut the last one
-  off part-way through — the rest of the week was simply missing. The widget was
-  sizing its columns from the width the launcher reported, which is not the width
-  it is actually drawn into, so the columns came out too wide to fit. Nothing in
-  either widget is measured any more: they draw at the size you pick under
-  Settings → Widgets. The month widget can no longer be resized narrower than its
-  grid needs, either ([#103], [#51]).
-- A month-grid widget stays a month grid. Since 2.16.0 a placed month widget
-  could redraw itself as the agenda widget a little after any change to your
-  events, because the release build merged the two widgets into a single class
-  and Android could no longer tell which of them a widget on your home screen
-  was ([#89]).
+- A month-grid widget stays a month grid, and draws all seven days again. Since
+  2.16.0 a placed month widget could redraw itself as the agenda widget a little
+  after any change to your events, and could draw only about four day columns
+  with the last one cut off part-way through. Both came from the release build
+  merging the two widgets into a single class, so Android could no longer tell
+  which of them a widget on your home screen was — and the month grid was handed
+  the wrong widget's measurements to lay its columns out against ([#89], [#103]).
 - The back gesture on **Settings → Views** returns to Settings instead of
   leaving Settings altogether and dropping you on the calendar. Special dates
   did the same ([#81]).