chore: add license headers to accesscontrol files

[joe0BAB]

No description provided.

[docker-agent]

Assessment: 🟢 APPROVE

This PR adds Apache 2.0 license headers to four access-control source files — a purely mechanical change with no functional impact. No logic, security, or correctness problems were introduced.

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MINOR finding: Missing trailing newline at end of file (all 4 files)

All four modified files now lack a trailing newline. The diff shows \ No newline at end of file on the last + line of each file after the license header was prepended:

• x/api/accesscontrol/accesscontrol.go (last line: })
• x/api/accesscontrol/accesscontrol_darwin.go (last line: ))
• x/api/accesscontrol/accesscontrol_linux.go (last line: })
• x/api/accesscontrol/accesscontrol_windows.go (last line: ))

POSIX defines a text file as ending with a newline. While Go tooling handles missing trailing newlines gracefully, some linters and diff tools may flag this. A newline was present before this PR (the original files end with } or ) followed by \n); the license-header prepend process appears to have stripped it. Adding a blank final line to each file would restore the trailing newline.