Improve second cursor visualization and motion quality

[TheGuyWithoutH]

Summary

Polish the visible helper cursor so it feels closer to a second user on the machine.

Why

The current overlay cursor is functional, but the bundled Codex cursor still feels more refined in shape, motion, appearance timing, and disappearance behavior.

Scope

• Continue tuning the cursor shape and glow treatment.
• Refine motion timing, easing, and travel visibility.
• Improve fade-in and fade-out behavior.
• Review whether click/scroll/drag pulses should differ visually.
• Keep the overlay independent from the system cursor.

Acceptance Criteria

• The cursor feels intentional and readable across short and long moves.
• Fade and pulse behavior feel polished rather than debug-like.
• Changes do not break pointer actions or focus restore.

[TheGuyWithoutH]

Progress update: the overlay cursor is now validated in the Stage Manager flow with the expected z-order: below Codex, above the target Calculator window. A crash in delayed overlay hiding was fixed by moving AppKit mutations back to the main thread. Keeping this issue open for remaining visual polish: shape, easing, pulse variants, and fade timing.

[TheGuyWithoutH]

Progress update: cursor observability is now expanded beyond pointer actions. The overlay appears during list/state reads, app activation, text input, and pointer actions; timeout refreshes across tool calls; movement now rotates toward travel direction; the activity wiggle, pulse, and settle animations were slowed; and the overlay geometry was padded/re-anchored to avoid right-facing tail clipping while keeping the cursor tip aligned. README now documents the broader cursor observability behavior.