Add scoring bonus for matches toward the end of path

[SakolB]

Description

Currently, the FZF v2 scoring algorithm gives bonuses for:

• First character match (bonusFirstChar)
• Path separator match (bonusPathSeparator)
• Consecutive matches (bonusConsecutive)

However, there's no bonus for matches that occur toward the end/right side of the path. Matches closer to the end of the path should be scored higher, as they typically match more specific parts of the directory name.

Rationale

Given a query like "test":

• /project/old/test - match at position 12 (end)
• /test/old/project - match at position 1 (beginning)

The first path should score higher because the match is closer to the actual directory name rather than an ancestor directory.

Expected Behavior

Matches occurring toward the right/end of the path should receive a scoring bonus proportional to their position. This gives preference to:

1. Matches in the filename/directory name itself
2. Matches in recent path components
3. Matches closer to the target rather than in ancestor directories

Current Behavior

All matches are scored equally based on:

• Base match score
• Position-based bonuses (first char, path separator)
• Consecutive match bonus
• Gap penalties

But no consideration for how far right the match occurs in the path.

Proposed Solution

Add a position-based bonus in the scoring algorithm:

// In the constants section (around line 10-18):
const bonusEndPosition = 8

// In the DP loop where bonuses are calculated (after line 223):
// Calculate position bonus - matches toward the end get higher scores
positionBonus := (j * bonusEndPosition) / tgLen
bonus += positionBonus

This would reward matches that occur in the latter portion of the path.

How it works:

• Character at position 1: gets bonus ≈ 0
• Character at mid-point: gets bonus ≈ bonusEndPosition/2 = 4
• Character at end: gets bonus = bonusEndPosition = 8

Example:
For query "test" in paths:

• /project/old/test - characters match at positions ~13-16, each gets high bonus
• /test/old/project - characters match at positions ~1-4, each gets low bonus

The path with the match toward the end accumulates a higher total score.

Implementation Location

• internal/ranker/ranker.go - in the score() function
• Specifically in the FZF v2 DP algorithm where bonuses are calculated (around line 216-223)

Considerations

• The bonus should be subtle enough not to override other important factors (consecutive matches, path separators)
• May need to tune the bonusEndPosition constant value through testing
• Should integrate smoothly with existing scoring logic
• Scaling options (start with linear, can adjust later):
  • Linear (proposed): (j * bonusEndPosition) / tgLen - balanced approach
  • Quadratic: (j * j * bonusEndPosition) / (tgLen * tgLen) - strongly favors end
  • Threshold: Only give bonus if j > tgLen * 2/3 - bonus only for last third

Acceptance Criteria

• Matches toward the end of paths receive higher scores
• The bonus scales proportionally with position (further right = higher bonus)
• Existing scoring behavior (path separators, consecutive matches) is preserved
• Manual testing shows improved ranking for end-of-path matches
• No performance degradation in the scoring algorithm