Add LuckRing/TK18 ring support (Coolwear K6 protocol)

[saksham2001]

Summary

Adds support for the LuckRing / TK18 ring family (Shenzhen Coolwear/Kewo OEM, custom "K6" protocol on service F618, company ID 0xFF64) — reverse-engineered from the decompiled vendor app; no public documentation of this family existed before.

• New LuckRing* protocol stack in RingProtocol/ (framing, encoder, decoder, driver, history pager, sync engine, coordinator) + catalog entry, ring art, and registry wiring
• RingBLEClient now picks the BLE write type from the characteristic's properties — the TK18's write char is write-without-response only, and hardcoded .withResponse writes were silently discarded (device-agnostic fix, existing rings unaffected)
• Pushes the ring's auto-monitoring config (opcode 128) on connect — firmware default is off, so the ring would otherwise never log history on its own
• Promotes Colmi SmartHealth to full support (R99 verified on hardware; badge removed)
• Docs: new docs/hardware/luckring.md ring page (jring/colmi format), index + SIMSONLAB cross-links

Type of change

• 📟 New / improved wearable support (BLE driver layer)
• 📝 Docs only

How was this tested?

• Added / updated unit tests (PulseLoopTests) — 50+ new cases (framing, encoder, decoder, driver, history pager, pairing/capability gating)
• Ran the test suite locally — 692 tests, 0 failures
• Tested on a physical device with a real ring — model: TK18 (spot HR/SpO₂/HRV, battery, pairing, history sync confirmed; BP + overnight sleep pending)

Privacy & data

• This change does not send health data off-device without explicit user action.
• No secrets, API keys, or personal data are committed.

Checklist

• My code follows the project's style (SwiftLint passes).
• I ran the tests and they pass.
• I updated docs / README where relevant.
• I read the Contributing guide.