Make Studio keyboard-first and improve UI/UX #4

Problem

Studio should feel like a playable instrument first and a form-based editor second. At the moment, mapped performance keys can be routed to a focused form control instead of playback.

The current keyboard helper intentionally ignores input, select, button, and textarea targets. As a result, focusing a parameter or rack control can make note/octave attempts operate the UI—or do nothing—rather than reach the synth.

Desired behavior

Unmodified mapped performance keys should be dominant throughout Studio:

• Notes: A W S E D F T G Y H U J K
• Octave: Z X

Those keys should trigger playback even when an input, range, select, or button currently has focus. Modifier shortcuts (Cmd/Ctrl/Alt) and non-performance editing keys should continue to behave normally.

Implementation should keep keydown/keyup handling symmetric, prevent the focused control's default behavior for captured performance keys, and avoid stuck notes when focus, visibility, or connection changes.

Broader UI/UX pass

Use this issue for a focused Studio usability pass as well:

• improve hierarchy and discoverability across the browser, rack, inspector, and performance keyboard;
• make busy, preview, accepted, conflict, offline, empty, and computed/read-only states clear;
• improve responsive behavior and avoid cramped/overflowing controls;
• preserve accessible semantics and visible focus while keeping performance input dominant;
• add concise in-product guidance for keyboard play and parameter editing.

Acceptance criteria

• Mapped unmodified keys always reach playback regardless of the focused Studio control.
• Captured keys do not also type into, select, click, or otherwise operate the focused control.
• Modifier shortcuts and numeric/arrow/Enter/Escape parameter editing continue to work.
• Key release remains correct if focus changes between keydown and keyup.
• Tests cover focused number/range inputs, selects, buttons, ordinary document focus, modifiers, repeats, blur, and visibility changes.
• The main Studio workflows receive a visual/interaction polish pass on desktop and narrow viewports.
• Accessibility and keyboard navigation regressions are covered by tests where practical.