feat(todo): a pin in the map's middle, and what is around it (ADR 0033, D32)

The location picker fills the screen with its map, the search floating
over it. A pin stays in the middle, lifting while the map moves, as
Molly's; where it lands the instance names the address and lists the
places around, as Threema's. That is `nearby` on the search endpoint,
for those signed in, the point neither kept nor logged, counted among
the searches: two lookups, as a plain one finds house numbers alone.

Fixes the map's credit, which overflowed a phone and was pale on white.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Signed-off-by: Tizian 「ティツィアーン」 <raisondetredev@pm.me>

apps/todo/halkyon_todo_flutter/lib/l10n/app_en.arb

@@ -962,6 +962,18 @@
   "@locationRecent": {
     "description": "The location picker's places of the person's tasks."
   },
+  "locationNearby": "Or choose a nearby place",
+  "@locationNearby": {
+    "description": "Above the places around the pin in the location picker."
+  },
+  "locationZoomIn": "Zoom in",
+  "@locationZoomIn": {
+    "description": "The location picker's button zooming the map in."
+  },
+  "locationZoomOut": "Zoom out",
+  "@locationZoomOut": {
+    "description": "The location picker's button zooming the map out."
+  },
   "locationPin": "Pinned place",
   "@locationPin": {
     "description": "The name of a pin placed by hand where nothing names the spot."