ci: refactor and add caching, use macOS-26 image for iOS

[artus9033]

Summary

This PR:

• changes the runner image for iOS to macOS-26
• extracts step paths that are repeated across different workflows / jobs
• adds ccache & performs caching
• adds caching of derivedDataDir in iOS builds
• adds caching of build artifacts for all Android projects (only TesterIntegrated has been covered so far)
• removes Turbo from apps/* - the builds are cached manually
• separates two iOS jobs that run in parallel: TesterIntegrated and (RNApp+AppleApp - since AppleApp consumes RNApp's output artifacts)
• fixes Turbo cache not containing prebuilt JS artifacts of CLI & brownie

Test plan

CI green.

[thymikee]

ship it whenever you're ready

[artus9033]

Thanks! Just assessing the boost we get from ccache and then merging!