fs git_status mangles non-ASCII paths (quoted porcelain output parsed verbatim)

Summary

A tracked file whose path contains non-ASCII characters (e.g. output/2026-08-31-总能等到回踩的.md) shows up in the kimi code web/desktop changes tree as a bogus directory chain like:

"my-ai-workspace
  output
    2026-08-31-bilibili-BV175t86pEre-26.8.31-
      346
        200
          273
            ...
              204.md"

Root cause

git status --porcelain=v1 --branch is invoked without -z in both engines:

• v2: packages/agent-core-v2/src/app/git/gitService.ts (status())
• v1: packages/agent-core/src/services/fs/fsGitService.ts (status())

With git's default core.quotePath=true, any path containing non-ASCII bytes is C-quoted in the output:

 M "my-ai-workspace/output/...-\346\200\273\350\203\275....md"

parsePorcelain (v2 agent-core-v2/src/app/git/gitParsers.ts, v1 agent-core/src/services/fs/fsGit.ts — the two parsers are byte-identical copies) then:

1. takes the quoted string verbatim as the path (never strips the surrounding quotes, never decodes the octal escapes), and
2. runs it through a posix() helper that does replaceAll("\\", "/") (v2) / split(path.sep).join("/") (v1, on Windows), which turns every \3xx octal escape into a fake path segment.

The resulting wire key is "my-ai-workspace/output/...-/346/200/273/.../204.md", which the web/desktop changes tree splits on / — producing the directory chain above.

Impact

• Changes tree renders non-ASCII paths as nonsense directory chains (leading quote glued to the first segment, trailing quote after .md).
• Clicking such a file requests a diff for the mangled path → diff fails.
• Rename entries are mangled the same way (the -> new half stays quoted).
• pathFilter matching silently misses these paths.
• ASCII-only paths are unaffected.

Reproduced against real git

$ git status --porcelain=v1 --branch
 M "my-ai-workspace/output/2026-08-31-bilibili-BV175t86pEre-26.8.31-\346\200\273\350\203\275\347\255\211\345\210\260\345\233\236\350\270\251\347\232\204.md"

$ git status --porcelain=v1 -z | od -c   # raw UTF-8, NUL-terminated, never quoted

$ git -c core.quotePath=false status --porcelain=v1
 M my-ai-workspace/output/2026-08-31-bilibili-BV175t86pEre-26.8.31-总能等到回踩的.md

With -z, rename records become XY new\0old (new path first, no -> separator).

Suggested fix

Add -z to the porcelain invocation and parse NUL-separated records in parsePorcelain (both engines). The posix() helpers can be dropped entirely — git porcelain already emits / separators on every platform, and keeping them would mangle legitimate POSIX filenames containing backslashes.

Start with status() in packages/agent-core-v2/src/app/git/gitService.ts and packages/agent-core/src/services/fs/fsGitService.ts, then compare parsePorcelain in the two parser files named in the issue. Trace how porcelain records reach the changes tree, including rename handling. Done means NUL-separated output preserves non-ASCII and backslash-containing paths, while path filtering and renames continue to work in both engines.