Improve typegap report table rendering

[rogerchappel]

What changed

• Fixed text report rendering so the file list has one surrounding table border instead of a closing border after every file row.
• Added regression coverage with multiple files in the report.

Why it matters

The CLI report is easier to scan and looks less broken in terminal output, especially for projects with many files.

Verification

• npm run release:check: passed
• vitest run --coverage: 69 tests passed during release:check
• npm run smoke rendered the fixture report with a single file table border.

Remaining limitations

• This is presentation-only and does not change coverage calculations.