fix(windows): context menu "Open Warp in new tab" navigates to home dir (#9844)

[KuaaMU]

Summary

• parse_tab_path trims trailing whitespace from the decoded path, catching an edge-case where %1/%V expansion appends invisible characters
• path_if_directory falls back to std::fs::canonicalize() when is_dir() returns false, resolving symlinks, ./.. segments, and other minor path normalization issues before giving up
• on_open_urls has a Windows-only fallback: if Url::parse() fails on a bare C:\... path, it converts to a file:/// URL before retrying

Root cause

The Windows Explorer context menu passes raw filesystem paths via %1/%V without URL-encoding them into the warp:// URI query string. While the url crate handles bare backslashes and drive-letter colons correctly in most cases, the resulting PathBuf can still fail the is_dir() gate in path_if_directory() — for example when the OS needs a canonicalized form (symlinks, trailing separators, \?\ prefix, etc.). When that happens the initial directory is silently dropped and the new tab falls back to ~.

Verified by running actual Rust tests:

Input: warp://action/new_tab?path=C:\Projects\my-app
  decoded: "path"="C:\Projects\my-app"   ← correct
  PathBuf: "C:\Projects\my-app"           ← correct

The URL parsing itself works fine — the issue is downstream in path_if_directory where is_dir() can fail for paths that need canonicalization.

Test plan

• Right-click a folder in Windows Explorer → "Open Warp in new tab" → verify it opens at the selected directory
• Right-click empty space inside a folder → "Open Warp in new tab" → verify it opens at the current directory
• Right-click a folder with spaces in the name → verify it works
• Right-click a folder that is a symlink/junction → verify it resolves correctly
• "Open Warp in new window" variants also work

Closes #9844
Related: #6665 (Linux counterpart), #6143 (duplicate instances)

🤖 Generated with Claude Code

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@KuaaMU

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