Kanata: Add advanced macro timing and macro-repeat

[malpern]

Problem

Kanata supports advanced macro features but KeyPath only supports basic macros:

• Timed macros (delays between keys)
• Dynamic macros (record on-the-fly)
• Macro-repeat variants

Current State

Basic macro support only - simple key sequences without timing.

Impact

Users can't create sophisticated macros with precise timing.

Fix

1. Add timing controls to macro editor
2. Support macro-repeat syntax
3. Consider dynamic macro recording UI (Phase 2)

References

• Comprehensive review: docs/code-review/comprehensive-feature-review.md section 4