fix(repo): preserve RepoMetadata on FS cache hit

[DmitriyLewen]

Description

This PR fixes an inconsistency where local FS Artifact.Inspect() returned an artifact.Reference without RepoMetadata on cache hits. As a result, repository context (repo URL, branch, tags, commit, author, etc.) was lost when the result came
from cache, diverging from the non-cached path.

Changes:

• Populate RepoMetadata from a.repoMetadata in the cache-hit path of pkg/fanal/artifact/local/fs.go.
• Update pkg/fanal/artifact/repo/git_test.go to assert RepoMetadata fields (RepoURL, Branch, Tags, Commit, CommitMsg, Author, Committer).

Examples:

Before:

➜ trivy repo -f json -o repo.test --cache-dir .cache --scanners=secret -q https://github.com/test/repo/
➜ jq '.Metadata.RepoURL' repo.test    
"https://github.com/test/repo/"


➜ trivy repo -f json -o repo.test --cache-dir .cache --scanners=secret -q https://github.com/test/repo/
➜ jq '.Metadata.RepoURL' repo.test    
null

After:

➜ trivy repo -f json -o repo.test --cache-dir .cache --scanners=secret -q https://github.com/test/repo/
➜ jq '.Metadata.RepoURL' repo.test    
"https://github.com/test/repo/"


➜ trivy repo -f json -o repo.test --cache-dir .cache --scanners=secret -q https://github.com/test/repo/
➜ jq '.Metadata.RepoURL' repo.test    
"https://github.com/test/repo/"

Related issues

• Close bug(repo): Trivy doesn't show repository metadata if the scan cache contains this scan. #9388

Related PRs

• feat(repo): add git repository metadata to reports #9252

Checklist

• I've read the guidelines for contributing to this repository.
• I've followed the conventions in the PR title.
• I've added tests that prove my fix is effective or that my feature works.
• I've updated the documentation with the relevant information (if needed).
• I've added usage information (if the PR introduces new options)
• I've included a "before" and "after" example to the description (if the PR is a user interface change).