fix(patch): parse Windows drive-letter paths

[ilepn]

Why

On Windows, apply_patch headers like "*** Update File: D:..." were truncated at the drive letter because the patch header parser split on ':'; this produced paths like 'D' and caused apply_patch to fail.

Fixes #10360.

What

• Parse patch header paths by slicing after the known header prefix instead of splitting on ':'
• Add regression tests for drive-letter update and move paths

Test

• bun test test/patch/patch.test.ts

[github-actions]

The following comment was made by an LLM, it may be inaccurate:

No duplicate PRs found

[ilepn]

Note: I ran a headless ApplyPatchTool check with Windows path variants. Drive-letter, UNC (\localhost\c$...), and ADS paths worked end-to-end. The ?\ long-path form still fails later in ApplyPatchTool due to path.resolve normalization (separate issue). The ?\ parser test is kept to ensure header parsing preserves the path string.

[machinekoder]

I independently arrived at the same fix on Windows (see #13582) and can confirm this resolves the issue. Tested on Windows 11 — patches with absolute drive-letter paths like D:\repos\project\src\file.ts now parse correctly instead of truncating to just the drive letter.

Happy to close my duplicate PR if this one gets merged.