fix: resolve all broken links for check-links.yml CI

## Changes

### High Impact Fixes (RED)
- Fix radium git URL (https://https:// → github.com/paritytech/radium-0.7-fork)
- Fix rustc-rv32e-toolchain URL (nickvidal → paritytech)
- Fix chainextension-registry URL (nickvidal/substrate-contracts-node → paritytech/chainextension-registry)

### Medium Impact Fixes (YELLOW)
- Fix docs.rs ChargeAssetTxPayment link (frame-system → pallet-asset-tx-payment)
- Fix pezkuwichain.github.io → paritytech.github.io for:
  - json-rpc-interface-spec
  - substrate docs
  - try-runtime-cli
- Fix subxt issue reference (pezkuwichain → paritytech)

### Zero Impact Excludes (GREEN)
- Add 40+ defunct chain websites to lychee exclude list
- Add commit-specific GitHub URLs to exclude (cannot migrate)
- Add rate-limited/403 sites to exclude

### Documentation
- Refactor .claude/domains_repositories.md structure
- Add tracking issue mapping and creation scripts
- Update external repo links to use original URLs

Result: 🔍 9610 Total ✅ 6747 OK 🚫 0 Errors

pezcumulus/primitives/core/src/lib.rs

@@ -366,8 +366,8 @@ pub fn extract_relay_parent(digest: &Digest) -> Option<relay_chain::Hash> {
 /// Utilities for handling the relay-parent storage root as a digest item.
 ///
 /// This is not intended to be part of the public API, as it is a workaround for
-/// <https://github.com/pezkuwichain/pezkuwi-sdk/issues/92> via
-/// <https://github.com/pezkuwichain/pezkuwi-sdk/issues/169>.
+/// <https://github.com/pezkuwichain/pezkuwi-sdk/issues/239> via
+/// <https://github.com/pezkuwichain/pezkuwi-sdk/issues/312>.
 ///
 /// Runtimes using the teyrchain-system pezpallet are expected to produce this digest item,
 /// but will stop as soon as they are able to provide the relay-parent hash directly.