docs: fix incorrect rustchain.org URLs in CONTRIBUTING.md

[wuxiaobinsh-gif]

Summary

Fix incorrect rustchain.org URLs in CONTRIBUTING.md to point to the actual live node at 50.28.86.131.

Changes

1. Live Infrastructure table: Updated Node Health URL from https://rustchain.org/health to https://50.28.86.131/health
2. Development Setup curl examples: Updated all three curl examples to use https://50.28.86.131 instead of https://rustchain.org
3. "What Gets Merged" section: Updated the live node reference from rustchain.org to 50.28.86.131

Testing

Verified the correct endpoint works:

curl -sk https://50.28.86.131/health
# Returns: {"ok":true,"version":"2.2.1-rip200",...}

Fixes #2783

[Scottcjn]

@wuxiaobinsh-gif — thanks for the breadth of fixes. Reviewing the 14 commits in this PR, I count at least 6 different bounties bundled together:

1. CONTRIBUTING.md URL fix
2. Explorer trailing-slash fix (README)
3. install.sh comment fix
4. ARM NAS/SBC hardware note
5. Telegram bot (bounty Security: Hardened G4 Server Proxy #2869) — separate large feature
6. _handle_get_state arity fix (bug [BOUNTY: 25 RTC] _handle_get_state calls _signed_content with wrong arity (TypeError when STATE requested) #2288) — competes with Fix TypeError in _handle_get_state #2311, [#2288] Fix _handle_get_state arity + live GossipLayer regression test #2312, fix: resolve _handle_get_state arity mismatch [#2288] #2301
7. Whitepaper duplicate removal (overlaps docs: remove duplicate whitepaper v0.97.pdf #2671)
8. Multiplier inconsistency (Modern PC 0.8x not 1.0x)
9. Architecture diagram raw-IP→domain (overlaps docs: replace raw IP with domain in architecture diagram #2670)
10. Miner download URLs (overlaps fix: correct miner download URLs in install.sh #2691, fix: correct miner download URLs in install.sh #2684)

Per our one-bounty-per-PR rule, this is too much in one PR — and several pieces compete with your own other open PRs (#2670, #2671, #2691). The merge queue can't pick a winner cleanly.

Action: I'm closing this PR. Please reopen each fix as its own focused PR. We'll pay each one individually — that's actually MORE total RTC than bundling, not less. Looking at your current open PRs, please:

• Pick ONE of docs: replace raw IP with domain in architecture diagram #2670 / docs: remove duplicate whitepaper v0.97.pdf #2671 / docs: fix node URL to 50.28.86.131 in INSTALL.md #2289 for the architecture-diagram URL direction (they fight each other)
• Pick ONE of fix: correct miner download URLs in install.sh #2691 / fix: correct miner download URLs in install.sh #2684 for the miner download URLs (you submitted twice)
• Open the Telegram bot as its own clean PR — bounty Security: Hardened G4 Server Proxy #2869 is open and waiting
• For [BOUNTY: 25 RTC] _handle_get_state calls _signed_content with wrong arity (TypeError when STATE requested) #2288 bug fix, see the trio (Fix TypeError in _handle_get_state #2311, [#2288] Fix _handle_get_state arity + live GossipLayer regression test #2312, fix: resolve _handle_get_state arity mismatch [#2288] #2301) — we're picking a winner separately, you can stand down on that one

When you've split, ping me here and I'll prioritize review.

[zp6]

Claim Submission — Star + File Bug Report (1 RTC)

What I did:

1. ⭐ Starred the Rustchain repo
2. 🐛 Filed bug report: Faucet rate limit has race condition and timezone mismatch

The bug report documents two real issues in faucet.py:

• Race condition (TOCTOU): can_drip() and record_drip() are non-atomic, allowing concurrent requests to bypass the 24-hour rate limit
• Timezone mismatch: SQLite CURRENT_TIMESTAMP is UTC but compared against local time via datetime.now(None), making rate limiting inaccurate on non-UTC servers

Both issues include reproduction steps and suggested fixes.

• GitHub username: @zp6
• Wallet: zp6