Add initial mobile app prototypes and staff payments feature

Introduces the first versions of client and staff mobile application prototypes, including platform-specific assets, screens, and configuration for Android, iOS, macOS, Linux, and Windows. Adds documentation, AI prompt guides, and a new staff payments feature module with repository, use cases, and presentation logic. Also includes generated localization files and supporting resources for both client and staff apps.

apps/mobile/ai_prompts/4-data-connect-mock.md

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+TASK: Create the data_connect package as a mockable abstraction layer.
+
+You must:
+1. Define abstract repositories for each domain group
+2. Create fake/mock implementations using in-memory data
+3. Simulate async GraphQL-style behavior
+4. Ensure replaceability with real generated SDK later
+
+Rules:
+- No Firebase imports
+- No HTTP
+- No direct entity mutation
+- Return domain entities ONLY
+
+Must follow archtiecture principles defined in:
+- docs/01-architecture-principles.md
+
+Must Follow Agent rules defined in:
+- docs/02-agent-development-rules.md
+
+Include:
+- Interfaces
+- Fake implementations
+- Clear TODO markers for real SDK replacement
+
+This package must compile and be dependency-safe.