Add anonymous analytics to release builds

[SunkenInTime]

Summary

• Adds a small anonymous analytics layer backed by PostHog, including install-scoped IDs, opt-out support, and privacy-safe event capture.
• Logs key usage events such as app opens, strategy creation/import, lineup creation, and content exports with minimal properties.
• Adds a new Privacy section in Settings so users can disable analytics.
• Wires release builds and CI to pass POSTHOG_PROJECT_TOKEN securely via temporary Dart defines, and documents the analytics setup.
• Bumps the app version to 4.5.1+94 and includes the new release metadata.

Testing

• Not run.
• Verified the release scripts now create and clean up temporary Dart-defines files when analytics is configured.
• Verified analytics is initialized after Hive boxes are opened and before normal app usage begins.
• Verified the Settings UI exposes an opt-out toggle under Privacy.
• Verified the tracked events are limited to anonymous product events with no strategy content or personal data.

[greptile-apps]

Greptile Summary

This PR adds anonymous analytics for release builds. The main changes are:

• PostHog capture service with install-scoped IDs and opt-out storage.
• Privacy settings toggle for anonymous analytics.
• Usage events for app opens, strategy actions, lineup creation, and exports.
• Release scripts and workflows that pass PostHog Dart defines through temporary files.
• Version and release metadata updates for 4.5.1+94.

Confidence Score: 5/5

This looks safe to merge.

• No blocking issues found in the changed code.

Important Files Changed

Filename	Overview
scripts/build_store_release.ps1	Cleans the Windows build output, builds Windows with optional PostHog Dart defines, and packages the existing build.
scripts/build_desktop_release.ps1	Adds temporary Dart-define file handling for desktop release builds.
lib/services/analytics_service.dart	Adds anonymous analytics capture, install ID storage, opt-out state, and no-op behavior when analytics is not configured.
lib/widgets/settings_tab.dart	Adds the Privacy settings section and analytics toggle.

_{Reviews (4): Last reviewed commit: "Prevent stale Store build packaging" | Re-trigger Greptile}

[SunkenInTime]

Addressed the current Greptile review feedback in 21c98a7 and fixed the release-version CI failure in ca524a6.

@greptileai

[SunkenInTime]

Removed the nested MSIX argument forwarding in b36d587. The Store script now runs Flutter's Windows build directly with the Dart define file, then packages that output with MSIX rebuilding disabled.

@greptileai

[SunkenInTime]

Made the Store packaging handoff deterministic in 358PLACEHOLDER by clearing only the generated build/windows tree before Flutter compiles with the analytics defines. MSIX packaging now has no stale Windows output to fall back to and fails if the new build is absent.

[SunkenInTime]

Correction: the deterministic Store packaging fix is in 94e8281. The generated build/windows tree is cleared before Flutter compiles with the analytics defines, so MSIX has no stale output to package and fails if the fresh build is absent.

@greptileai

[greptile-apps]

Thanks for the clarification. That makes sense — clearing build/windows before the analytics-defines Flutter build ensures msix:create can only pick up freshly compiled binaries that include the PostHog token, and the hard failure (throw "No MSIX or Store upload package was found...") acts as a safety net rather than silently packaging stale output. The approach is sound.

[SunkenInTime]

The current head 94e8281 includes the deterministic clean-build handoff you confirmed as sound. Please run a full review of the current head and update the confidence score.

@greptileai