Fix duplicate path join in OS filesystem utility

[fnoopv]

References

Issue(s): N/A
Discussion: N/A

Description

Fix osfs.FS.FileExists and osfs.FS.IsDirectory when a base directory is configured with New(...).

Previously, both methods called path.Join(f.dir, name) before delegating to f.Stat(name). Since Stat already resolves the given path relative to the filesystem base directory, the base path was effectively joined twice. This caused lookups such as New("resources").FileExists("test_file.txt") and New("resources").IsDirectory("lang") to fail unexpectedly.

This PR removes the duplicated path.Join in both methods and adds regression tests covering FileExists and IsDirectory with a configured base directory.

Usage example

fs := osfs.New("resources")

exists := fs.FileExists("test_file.txt") // true
isDir := fs.IsDirectory("lang")          // true

Possible drawbacks

This change slightly alters the behavior of FileExists and IsDirectory for callers relying on the previous incorrect path resolution. However, the new behavior is consistent with the rest of the filesystem abstraction and with how Stat already handles base directories.

[coveralls]

Coverage Report for CI Build 26882796764

Coverage remained the same at 97.515%

Details

• Coverage remained the same as the base build.
• Patch coverage: 2 of 2 lines across 1 file are fully covered (100%).
• No coverage regressions found.

Uncovered Changes

No uncovered changes found.

Coverage Regressions

No coverage regressions found.

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Coverage Stats

Relevant Lines:	6882
Covered Lines:	6711
Line Coverage:	97.52%
Coverage Strength:	297.67 hits per line

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💛 - Coveralls

[System-Glitch]

This change slightly alters the behavior of FileExists and IsDirectory for callers relying on the previous incorrect path resolution. However, the new behavior is consistent with the rest of the filesystem abstraction and with how Stat already handles base directories.

Any patch affecting code relying on buggy behavior should not be considered a breaking change. This is fine.

[System-Glitch]

Merged. Thanks!