feat(mobile): implement first-launch KVKK privacy consent & location permission gate (#115)

[Decuayer]

🎯 Jira / Task Reference

• Jira Issue: SDDC-79
• GitHub Issue: Closes [SDDC-79] Implement First-Launch KVKK Privacy Consent and Location Permission Gate in Flutter #115
• Component: mobile

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📝 Summary of Changes

Implements a first-launch onboarding gate for the SOCAR Dispatch Flutter application in compliance with Section 5.1, Section 6.2 of the Design Document, and NFR-04 (Security & Compliance):

• Persistent Gate State: Integrated shared_preferences (^2.3.5) and created OnboardingRepository to persistently track has_accepted_kvkk and ISO-8601 acceptance timestamp.
• Onboarding & Location Permission Service: Added OnboardingPermissionService to orchestrate sequential system prompts (Permission.locationWhenInUse, Permission.locationAlways, and Permission.notification).
• BLoC Architecture: Implemented OnboardingBloc, events, and states for checking onboarding status, toggling consent agreement, and handling permission denial / permanent denial states.
• UI Components:
  • KvkkDisclosureBox: Scrollable disclosure box explaining emergency telemetry and data processing terms for industrial plants.
  • PermissionRationaleDialog: Educational prompt directing users to device settings if permissions are permanently denied.
  • KvkkConsentView: Consent view with interactive checkbox and "Continue & Grant Permissions" CTA button.
  • OnboardingGateView: Top-level route guard directing new installs to KVKK consent and subsequent launches directly to AuthGate.
• Testing: Added automated unit and widget test suite under test/features/onboarding/ validating persistence, BLoC transitions, and UI interaction.

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🏷️ Type of Change

• 🚀 Feature: New functionality or operational workflow
• 🐛 Bug Fix: Non-breaking fix for an identified defect
• ♻️ Refactor: Code restructuring without behavior alteration
• ⚡ Performance: Speed, query, or memory consumption optimization
• 🛠️ Chore / Infra: Dependencies, Docker, CI/CD, or tooling updates
• 📖 Documentation: README, API specs, or code documentation updates
• ⚠️ Breaking Change: Requires schema migration or API contract changes

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🧪 Testing & Verification

Automated Tests

• Mobile tests executed: flutter test (13/13 passed)
• Linter & formatting passed: flutter analyze (No issues found)

Manual Test Steps

1. Perform clean install or clear app preferences; verify that the app launches into KvkkConsentView.
2. Confirm the "Continue & Grant Permissions" button remains disabled until checking the consent box.
3. Tap "Continue & Grant Permissions" and confirm system location permission prompts are triggered.
4. Grant permissions and verify smooth navigation to LoginView (or active home view if session exists).
5. Terminate and restart the application; verify onboarding is bypassed directly to AuthGate.
6. Deny permissions permanently and verify the educational rationale dialog provides an "Open Settings" shortcut.

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📋 Pre-Merge Checklist

• My code adheres to the project's Clean Architecture & style guidelines.
• I have self-reviewed my own code before requesting review.
• Database migrations are backwards-compatible (not applicable).
• Sensitive secrets / tokens are NOT committed.
• Jira status updated to In Review.