Remove intro-skip detection and UI; keep only end-skip behavior

[FieteGM]

Motivation

• Remove the fragile/heuristic intro detection and automatic intro-skipping workflow and keep only a simple, deterministic end-screen skip behavior.
• Simplify the sidebar UI and stored state so users no longer need per-series intro start/end fields or external intro_times.json data.
• Align runtime settings and persisted progress.json with a reliable, minimal skip model to improve robustness.

Description

• Deleted the entire intro-detection workflow and related helpers, including get_intro_skip_seconds, get_intro_skip_end_seconds, set_intro_skip_seconds, load_intro_times, get_default_intro_times, detect_intro_start, and smart_skip_intro from SerienJunkie/s.toBot.py and removed SerienJunkie/intro_times.json and SerienJunkie/README_INTRO_DETECTION.md.
• Replaced the old skip_intro action with a typed seek_to_position(driver, seconds: int) helper and updated all callsites to use seek_to_position for deterministic seeking.
• Removed autoSkipIntro from runtime settings and settings.json, and removed intro start/end inputs and debounced handlers from the sidebar UI, leaving only end-skip controls (bw-end) and corresponding handling code in s.toBot.py and the injected JS UI.
• Cleaned persisted sample data in SerienJunkie/progress.json by removing stored intro_skip_start/intro_skip_end entries and updated README.md to reflect the end-skip-only behavior.

Testing

• No automated tests were executed for this change.

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Codex Task