Fix missing matchedText key in JSON result

[armandabric]

This pull request improves the handling of text matches in search results, specifically addressing cases where GitHub omits the matched text. The main changes ensure that the matched text is accurately derived from the fragment when necessary, and that the output remains consistent.

Text match derivation and normalization:

• Added a new function deriveSegmentText in src/api.ts to extract the matched text from the fragment using indices when GitHub does not provide the text. This function is now used when processing search results. [1] [2]
• Updated the test suite in src/api.test.ts to verify that segment text is correctly derived from the fragment when omitted by GitHub.

Test and comment improvements:

• Clarified the comment in src/output.test.ts to reflect that empty segment text should not emit matchedText in the JSON output.

[github-actions]

Coverage after merging fix/missing-matched-text-attibutes into main will be

95.89%

Coverage Report

File	Stmts	Branches	Funcs	Lines	Uncovered Lines
src
aggregate.ts	100%	100%	100%	100%
api-utils.ts	93.20%	100%	93.75%	93.13%	101–103, 65, 73, 86–87, 91–92
api.ts	94.80%	100%	100%	94.14%	331–335, 396, 413, 75–81
cache.ts	94.67%	100%	100%	94.29%	139–141, 39
completions.ts	99.42%	100%	100%	99.37%	270
group.ts	99.50%	100%	97.44%	100%
output.ts	99.29%	100%	95.65%	99.61%	80
regex.ts	99.26%	100%	100%	99.21%	251
render.ts	89.87%	100%	89.47%	89.89%	167, 191–196, 198–200, 202–203, 254–255, 276, 463–464, 487–489, 555–559, 571–572, 577–584, 586–594, 596–597
upgrade.ts	88.38%	100%	94.44%	87.89%	128, 131, 133, 153, 167–168, 188–195, 198–204, 209, 214, 250–253
src/render
filter-match.ts	97.44%	100%	92.31%	100%
filter.ts	100%	100%	100%	100%
highlight.ts	96.63%	100%	90.40%	99.31%	284–285
rows.ts	97.58%	100%	100%	97.44%	168, 54–55
selection.ts	100%	100%	100%	100%
summary.ts	100%	100%	100%	100%
team-pick.ts	100%	100%	100%	100%

[Copilot]

Pull request overview

This PR fixes missing matchedText in JSON output by deriving match segment text from the fragment using GitHub-provided indices when seg.text is omitted, keeping output consistent and improving downstream rendering.

Changes:

• Added deriveSegmentText() in src/api.ts to compute segment text from fragment + indices when GitHub omits the text field.
• Updated fetchAllResults() normalization to use the derived segment text instead of defaulting missing text to "".
• Added a unit test in src/api.test.ts to validate derived segment text behavior; clarified an existing comment in src/output.test.ts.

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated no comments.

File	Description
src/api.ts	Derives missing text-match segment text from fragment and indices during result normalization.
src/api.test.ts	Adds coverage ensuring omitted seg.text is correctly derived from the fragment.
src/output.test.ts	Updates wording to reflect that empty segment text should not emit matchedText in JSON.