fix(calldata): align toString output with the reference format

[memosr]

Fixes #210

What

Fixes three defects in abi.calldata.toString() (src/abi/calldata/string.ts):

• Bytes and addresses are now zero padded to two hex digits per byte
• Map entries are now separated by commas
• Arrays no longer emit a trailing comma

Adds tests/calldata-to-string.test.ts, mirroring the reference test suite at runners/genlayer-py-std/tests/test_calldata_to_str.py in the genvm repo.

Why

The output did not match the reference implementation (runners/genlayer-py-std/src/genlayer/calldata/__init__.py, to_str):

Input	before	reference
new Uint8Array([0x01, 0x02])	b#12	b#0102
20-byte address of 0x01	addr#11111111111111111111	40 hex chars
{x: true, y: null}	{"x":true"y":null}	{"x":true,"y":null}
[1, 2, 3]	[1,2,3,]	[1,2,3]

The missing hex padding is lossy rather than cosmetic: Uint8Array([0x01, 0x02]) and Uint8Array([0x12]) both rendered as b#12, so distinct values collapsed to the same string. Addresses rendered shorter than 40 characters whenever a byte was below 0x10.

This is public API and also feeds the readable field of decodeTransaction / simplifyTransactionReceipt via calldataToUserFriendlyJson, so the malformed output was user visible.

Testing done

• Added 6 tests covering bytes, addresses, maps, arrays, nesting, and the byte-array collision case. All fail on v1 before the fix and pass after.
• Full suite: npx vitest run --typecheck gives 82 passed, no type errors. Baseline before the change was 76 passed, so no regressions.
• npx eslint src/abi/calldata/string.ts tests/calldata-to-string.test.ts is clean.

Decisions made

• Expected values were taken from the genvm reference rather than invented, so the SDK matches genlayer-py output.
• src/abi/calldata/string.ts does not satisfy prettier --check on v1 today, before this change. I left the formatting untouched so the diff stays reviewable. Happy to add a separate formatting commit if you'd prefer.
• Targeting v1 per CONTRIBUTING, since this is a bug fix. The same defects are present on v2, v2-dev and main; let me know if you want a companion PR.

Checks

• I have tested this code
• I have reviewed my own PR
• I have created an issue for this PR
• I have set a descriptive PR title compliant with conventional commits

Reviewing tips

The diff is 15 lines in string.ts. The comma changes follow the same first flag pattern the reference uses. The two padStart(2, "0") calls are the lossy part worth checking first.

User facing release notes

abi.calldata.toString() now produces output matching the GenVM reference format. Byte and address values are zero padded, map entries are comma separated, and arrays no longer include a trailing comma. This also affects the readable field returned by decodeTransaction and simplifyTransactionReceipt.

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