Fix home row mod timing to prevent false positives

[rzlink]

Problem

Users experiencing issues where home row mods produce unintended character combinations (e.g., 'fi' instead of 'I' when using Shift+F with I).

Solution

This PR improves home row modifier timing to reduce false positives:

Changes Made

• Increased standard tapping term: 200ms → 280ms for better hold detection
• Added strict hold-tap behavior: New ht_strict behavior for problematic keys
• Shift-specific tuning: Applied strict timing (300ms, tap-preferred) to shift keys
• Updated prior-idle timing: 120ms → 150-200ms to prevent accidental holds
• Documentation: Updated README with detailed behavior explanations

Technical Details

• LSHIFT_F, RSHIFT_J, LSHIFT_T, RSHIFT_N now use ht_strict
• Strict behavior uses tap-preferred flavor to prioritize taps over holds
• Longer timing windows give more time for proper hold detection
• Different timing for different modifier types optimizes typing experience

Benefits

• Significantly reduces 'false positive' modifier activations
• Maintains responsive typing feel for non-problematic keys
• Provides better distinction between intentional holds and fast typing
• Documented configuration makes it easier for others with similar issues

Testing

Please test this configuration and report if you still experience issues with:

• Shift combinations producing unwanted characters
• Other home row mod false positives
• Any reduction in typing responsiveness

Closes #[issue-number-if-exists]

[Copilot]

Pull Request Overview

This PR addresses false positive issues with home row modifiers by implementing differentiated timing configurations to reduce unintended character combinations while maintaining typing responsiveness.

• Increased standard tapping terms and introduced strict timing behavior for problematic shift keys
• Added comprehensive documentation explaining the two-tier hold-tap timing system
• Applied stricter timing specifically to shift modifiers that were causing false positives

Reviewed Changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 1 comment.

File	Description
config/include/behaviors.dtsi	Adds new strict hold-tap behavior and increases timing parameters
config/corne.keymap	Updates shift key definitions to use strict timing behavior
README.md	Documents the dual hold-tap timing system and behavior rationale

[Copilot]

[nitpick] The global-quick-tap; property is duplicated between both hold-tap behaviors. Consider if this duplication is intentional or if the strict behavior should have different quick-tap settings.