Sync SECURITY.md from picosdk-repo-standards via GitHub Action

[AndrewAPico]

Summary

• Removes the per-repo copy of SECURITY.md from the repo root.
• Adds .github/workflows/sync-security-policy.yml, which copies SECURITY.md from picotech/picosdk-repo-standards into the repo root and commits it only when it has changed.

The workflow runs every Monday at 04:17 UTC and can also be started manually (workflow_dispatch).

After merging

Scheduled and manual runs use the workflow file on master, so the repo has no SECURITY.md until the first sync. Start it straight after merging:

gh workflow run sync-security-policy.yml -R picotech/picosdk-c-examples

or use Actions → sync-security-policy → Run workflow.

Notes

• Requires master to stay unprotected (the workflow pushes directly with GITHUB_TOKEN). If branch protection is added later, the workflow should be changed to open a PR instead.
• GitHub disables scheduled workflows in public repos after 60 days without repo activity; the manual trigger still works.

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