Increase playback speed range: expand upper and lower limits beyond current bounds

Start by locating ImprovedTube’s existing playback-speed controls and related settings, then inspect how they interact with the YouTube player API. Done means supporting slower playback and speeds above the current upper bound without breaking the controls, with any configurable range behavior clearly defined.

⚬ PROBLEM: The current playback speed range in ImprovedTube is too narrow for power users. The upper speed limit caps out too low for efficient skimming, and the lower speed limit doesn't go slow enough for detailed frame-by-frame review or language learning. Users who want to browse through long content or carefully analyze segments are constrained by these artificial boundaries.

⚬ SOLUTION: Expand both ends of the playback speed range:

• Upper limit (increase): Should go at least up to 2x, ideally with the option to go higher (3x–4x) for advanced users who want to quickly skim through content.
• Lower limit (decrease): Should go below the current minimum to allow very slow playback (e.g., 0.25x or less) for detailed analysis, transcription, or language comprehension.
• Optionally allow the user to custom-configure their preferred min/max limits in the settings.

⚬ ALTERNATIVES:

• YouTube's native speed selector (limited to 0.25x–2x with fixed presets — no custom/smooth range)
• Browser-level video speed overrides (clunky, no UI integration, resets on each video)
• Other extensions like "Video Speed Controller" (separate extension, not integrated into ImprovedTube's unified menu)
• Keyboard shortcut-based step increments could approximate an extended range by multiplying steps

⚬ RELEVANCE / SCOPE:

• Power users who watch long-form content (lectures, tutorials, meetings, podcasts) and need fast skimming: ~20–30% of users
• Language learners & analytical viewers who need slow playback: ~10–15% of users
• Combined audience: ~30–40% of users would benefit from an extended range

⚬ "SIDE EFFECTS":

• Very high speeds (>4x) may cause audio distortion or sync issues on some devices — suggest capping at a safe max or showing a warning
• Additional menu entries could clutter the speed selector — solution: keep the current UI but add a "custom range" toggle in settings
• YouTube may change their player API and break extended speed functionality — need to account for that in implementation

⚬ CONTEXT: This is a long-standing limitation of YouTube's native player. Other video platforms and extensions already support wider ranges. ImprovedTube already enhances many YouTube player features; extending speed controls is a natural next step.

Thank you!