[Kimlimp]

Summary

Closes #359

Introduces an opt-in, experimental local timeshift buffer for live HLS streams on macOS, allowing users to pause, rewind, and scrub live broadcasts without requiring server-side catchup support.

What this does:

• Ingests rolling live HLS segments into a managed local cache directory (TimeshiftCache).
• Serves synthetic playlists to the player via a loopback HTTP server on 127.0.0.1 (TimeshiftServer).
• Adds a macOS timeshift timeline with -M:SS delay indicator and "Jump to Live" button.
• Adds user-configurable buffer limits and storage safety caps in Settings > Player.
• Improves EPG programme duration tracking and scrubber clamping for all platforms.

Type of change

• feat — new feature

Platforms verified

• iOS / iPadOS
• macOS
• tvOS
• visionOS

Checklist

• I opened an issue first (for features / non-trivial changes) and linked it above.
• My commits follow the Conventional Commits format.
• Pre-commit hooks pass (SwiftFormat, SwiftLint --strict, String Catalog normalization).
• The test suite passes (LumeTests + LumeUITests on at least the iOS simulator).
• New/changed user-facing text is localized in both en and de.
• I added or updated tests covering my change where it makes sense.
• My change contains no credentials, stream URLs, or other content.