feat(activities): add autocomplete & what's new popup

Features:
- Add autocomplete support for Activity search with Google Places API.
- Add "What's New" popup system to showcase new features on app update.
- Implement logic to detect fresh installs vs updates.

Fixes:
- Switch API key handling to use Firebase config for Release mode support.
- Refactor map pins to be consistent (red pins).
- UI fixes on Create Trip page (overflow issues).

Refactor:
- Make WhatsNewDialog reusable by accepting features list as parameter.

pubspec.yaml

@@ -16,7 +16,7 @@ publish_to: 'none' # Remove this line if you wish to publish to pub.dev
 # https://developer.apple.com/library/archive/documentation/General/Reference/InfoPlistKeyReference/Articles/CoreFoundationKeys.html
 # In Windows, build-name is used as the major, minor, and patch parts
 # of the product and file versions while build-number is used as the build suffix.
-version: 2026.1.2+1
+version: 2026.1.3+1
 
 environment:
   sdk: ^3.9.2