Feature: Playback speed controls (UI buttons + keyboard shortcuts)

[aliafshany]

Feature request

Add playback speed controls so users can change how fast audio/video plays back.

Proposed UI

• Playback speed buttons (or a speed picker/menu) in the player controls, e.g.:
  • Common presets: 0.5×, 0.75×, 1×, 1.25×, 1.5×, 1.75×, 2×
  • Optional: custom/fine-grained speed if that fits the player UX

Proposed keyboard shortcuts

Suggested defaults (adjust to match existing shortcut conventions):

Shortcut	Action
]	Increase playback speed
[	Decrease playback speed
\ or 0	Reset to 1×

(If [ / ] conflict with existing bindings, alternatives like Shift+. / Shift+, or Cmd+Shift+> / Cmd+Shift+< would work too.)

Why

• Faster review of long recordings/podcasts/talks
• Slower speed for language learning, dense technical content, or careful listening
• Keyboard control keeps hands on the keyboard during listening sessions

Acceptance criteria

• User can change playback speed from the player UI
• User can change (and reset) playback speed via keyboard shortcuts
• Current speed is visible in the UI
• Speed preference either persists for the session or is rememberable across launches (whichever fits app design)
• Shortcuts are documented (in-app help / settings / README)

Notes

Happy to refine presets, default shortcuts, or UI placement based on maintainer preference.