Fix(opencode): windows path separator session list

[shifttttttt]

fix(opencode): fix Windows path separator mismatch in session list

Issue for this PR

Closes #23864

Type of change

• Bug fix
• New feature
• Refactor / code improvement
• Documentation

What does this PR do?

Add a delimiter func to format project dir on windows , which deal with the mismatch probelm when open a old project through path.

How did you verify your code works?

1. run opencode web command
2. open a project aleardy handled.
3. check if the old sessions is avaliable.

Screenshots / recordings

Not a UI change.

Checklist

• I have tested my changes locally
• I have not included unrelated changes in this PR

[github-actions]

Hey! Your PR title Fix/windows path separator session list doesn't follow conventional commit format.

Please update it to start with one of:

• feat: or feat(scope): new feature
• fix: or fix(scope): bug fix
• docs: or docs(scope): documentation changes
• chore: or chore(scope): maintenance tasks
• refactor: or refactor(scope): code refactoring
• test: or test(scope): adding or updating tests

Where scope is the package name (e.g., app, desktop, opencode).

See CONTRIBUTING.md for details.

[github-actions]

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

Potential Duplicate PRs Found:

1. fix: normalize forward slashes to backslashes for Windows directory matching #28251 - "fix: normalize forward slashes to backslashes for Windows directory matching"

   • Very similar fix addressing Windows path separator normalization

2. fix(session): match Windows directory separators #28027 - "fix(session): match Windows directory separators"

   • Directly related to matching Windows directory separators in sessions

3. fix: sessions missing from sidebar on Windows due to path separator mismatch #23862 - "fix: sessions missing from sidebar on Windows due to path separator mismatch"

   • Addresses the same root issue (path separator mismatch on Windows affecting sessions)

4. fix(session): normalize session directory filters across path variants #28040 - "fix(session): normalize session directory filters across path variants"

   • Related normalization fix for session directory paths

5. fix: normalize Windows desktop session paths #26580 - "fix: normalize Windows desktop session paths"

   • Earlier attempt at normalizing Windows session paths

6. fix: normalize Windows session directory filters #26463 - "fix: normalize Windows session directory filters"

   • Related Windows session directory normalization

Why they're related: All these PRs address the same core issue—Windows path separator mismatches affecting session availability and sidebar display. There appear to be multiple overlapping attempts to fix issue #23864. You may want to review #28251 and #28027 especially, as they're very recent and likely address the same problem.