feat: add miner_online_checker

[CelebrityPunks]

Check if specific miner is online

[github-actions]

Welcome to RustChain! Thanks for your first pull request.

Before we review, please make sure:

• Your PR has a BCOS-L1 or BCOS-L2 label
• New code files include an SPDX license header
• You've tested your changes against the live node

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[achievefibromyalgia-lgtm]

Code Review: #1318

Verdict: ✅ Approved!

[Scottcjn]

Hey @CelebrityPunks — want to be upfront with you.

Your earlier work was genuinely excellent: the security audit (#990), CLI wallet (#991), block explorer (#1002), TUI dashboard (#1001) — that's real engineering and you earned every RTC of the 129 we paid.

But the recent batch of ~100 PRs (#1318–#1427) are all the same 20-line template with different filenames. wallet_sweep_dust.py doesn't sweep dust — it prints "Sweep small balances to main" and checks node health. Same code in every file.

We can't pay bounties for copy-pasted templates. That said, you're still a valued contributor with a track record of real work. If you want to pick up a bounty, the bounty board has real tasks at 3-15 RTC each. Your skills are clearly there — the security audit proved it.

Quality over quantity. One real tool > 100 template scripts.