fix(edit): use the family's text input, and show both times when zones differ

Two review fixes.

The zone picker's search box was a raw Material OutlinedTextField — the
only one left in the app, and against the convention DialogControls
states outright ("the family's InlineTextField over a tonal surface, not
Material's outlined field"). Rebuild it on InlineTextField over a tonal
surface, with the clear button inside the surface since the picker's top
bar is the title rather than a search field.

Showing a pinned event only in its own zone answered "what was it set
to?" while dropping "when is it for me?" — the user had to do the offset
arithmetic. Show both whenever they differ:

- the edit form keeps editing the event in its own zone (that's the time
  it was set at) and captions it with the local equivalent;
- the detail screen keeps local times primary and now leads the zone card
  with the original ("8:00 AM – 9:00 AM in New York") instead of naming
  the zone and nothing else.

EventForm.timesIn is pure, so the conversion — including crossing the
date line and each zone's own DST, which don't move together — is a
plain JUnit test rather than something only reviewable on a phone.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

app/src/main/res/values/strings.xml

@@ -107,6 +107,13 @@
     <string name="event_edit_timezone_all">All time zones</string>
     <string name="event_edit_timezone_none">No time zone matches “%1$s”</string>
     <string name="event_edit_timezone_clear">Use device zone</string>
+    <!-- Shown under the time fields when the event is pinned to another zone:
+         the same event expressed where the user actually is. %1$s is a time
+         range, e.g. "2:00 PM – 3:00 PM". -->
+    <string name="event_edit_timezone_local_time">%1$s your time</string>
+    <!-- The event's own zone times on the detail screen. %1$s is a time range,
+         %2$s the zone's city, e.g. "8:00 AM – 9:00 AM in New York". -->
+    <string name="event_detail_timezone_original">%1$s in %2$s</string>
 
     <!-- Event form — per-event color -->
     <string name="event_edit_color">Color</string>