Fix XCM v4 format issues and documentation inconsistencies

[Copilot]

• Fix XCM v4 Parachain junction values (convert strings to numbers in xcm-tests.js)
• Fix XCM v4 X1 interior format (remove array wrapping in xcm-tests.js)
• Fix Junctions::X1 pattern matching in xcm_config.rs
• Update documentation from XCM v5 to XCM v4 in ADDING_TESTS.md
• Remove changes to README.md (file deleted in base branch)
• Remove changes to run-tests.sh (simplified in base branch)
• Resolve conflicts with release/4.1 branch
• Rebase onto latest release/4.1

All XCM v4 format fixes and documentation updates have been applied on top of the latest release/4.1 branch.

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[akru]

@copilot fix issues in this PR and then I'll merge

[Copilot]

@copilot fix issues in this PR and then I'll merge

All review comments have been addressed in commit d23f39b:

Fixed XCM v4 format issues:

• Changed Parachain junction values from strings to numbers (parachainId.toString() → parachainId.toNumber(), '1000' → 1000)
• Fixed X1 interior format by removing array wrapping for AccountId32 junction
• Fixed Junctions::X1 pattern matching in xcm_config.rs to unwrap single junction correctly

Updated documentation:

• Changed all XCM v5 references to XCM v4 in README.md and ADDING_TESTS.md
• Added version configuration comments with upstream links in run-tests.sh

The changes are ready for merge.

[akru]

@copilot resolve conflicts

[Copilot]

@copilot resolve conflicts

I've resolved the conflicts locally and created a rebased version on top of release/4.1 (commit 5df092e). However, I cannot force-push the changes due to environment restrictions.

The conflicts were:

1. scripts/zombienet/README.md - Removed (deleted in release/4.1)
2. scripts/zombienet/run-tests.sh - Kept release/4.1 version (simplified, my version config comments no longer needed)

The rebased commit includes only the necessary XCM v4 fixes:

• Fixed Junctions::X1 pattern matching in xcm_config.rs
• Changed Parachain values from strings to numbers in xcm-tests.js
• Fixed X1 interior format for AccountId32 in xcm-tests.js
• Updated XCM v5 → v4 references in ADDING_TESTS.md

To complete the merge, you can either:

1. Force-push from your side: git push --force origin 5df092e:copilot/sub-pr-424
2. Or manually merge release/4.1 into this PR and keep the simpler run-tests.sh and remove README.md