Centralize and update analysis options configuration

Replaces the old analytics_options.yaml with a new analysis_options.yaml at the workspace root, consolidating lint rules and analyzer settings. Updates all references in subprojects to use the new file, and adds flutter_lints as a direct dev dependency in pubspec.yaml for consistent linting across the workspace.

apps/mobile/analysis_options.yaml

@@ -0,0 +1,26 @@
+include: package:flutter_lints/flutter.yaml
+
+analyzer:
+  exclude:
+    - "**/dataconnect_generated/**"
+    - "**/*.g.dart"
+    - "**/*.freezed.dart"
+    - "**/*.config.dart"
+  errors:
+    # Set the severity of the always_specify_types rule to warning as requested.
+    always_specify_types: warning
+
+linter:
+  rules:
+    # Every variable should have an explicit type.
+    - always_specify_types
+    
+    # Additional common best practices not always enforced by default
+    - prefer_const_constructors
+    - prefer_const_declarations
+    - prefer_final_locals
+    - avoid_void_async
+    - unawaited_futures
+    - sort_constructors_first
+    - camel_case_types
+    - library_private_types_in_public_api