Revert #778: gate EVM submitters at their EVM address, not the derived Zilliqa address

[frankmeds]

Reverts #778 (f0339c68).

Why

#778 derived a MetaMask user's Legacy/Zilliqa (SHA256) address from the signature and used it for the gZIL gate / scoring / members. That assumption was wrong: on Zilliqa, a MetaMask account holds its ZRC2 tokens (gZIL) at its EVM (Keccak) address, not at the legacy Zilliqa address.

Verified against a real account (same private key in MetaMask + ZilPay):

Account	Address	gZIL
EVM (MetaMask)	0x8307a100…167198 (zil1svr6zq…)	40 gZIL
Legacy/Zilliqa (SHA256)	0xaaA6833…035f34 (zil142ngx…)	0

The user signed in with MetaMask (the EVM account, which holds the 40 gZIL), but #778 normalized body.address to the legacy account (0xaaA6833…, empty) and the gate returned MIN_BALANCE. #778's derivation was correct (it does compute the legacy address) — but it pointed the balance check at the wrong one of the user's two accounts.

What this restores

The original behavior: gate/scoring/members use the address the user signed with (body.address):

• MetaMask signer → EVM address → gZIL[0x8307a100…] = 40 → passes.
• ZilPay (Legacy) signer → Zilliqa address → that account's gZIL → passes.

This is also the correct governance rule and avoids double-counting voting power: a user's gZIL is counted once, at the address controlled by the wallet they signed with (signing with the other wallet yields its own balance, typically 0). Forcing everyone onto the legacy address (keeping #778) would instead require every MetaMask holder to move their gZIL across accounts.

Scope

• Removes the zilliqaAddressFromEVMSignature helper + its test + the body.address normalization + the package.json test-script line (all of fix(governance-api): normalize EVM (MetaMask) submitters to their Zilliqa address #778).
• Keeps fix: DEVOPS-364 governance proposal creation 504 + stuck publish spinner #777 (504 fix, spinner fix, full voter-scoring snapshot, timeoutSec: 90) — unaffected.
• (fix(governance-api): require the signed message to match the submitted body #779, the sig.message === body.msg guard, is a separate open PR and is independent.)

Verify on staging

With MetaMask account 0x8307a100… (40 gZIL), create a gZIL-space proposal → expect 201; GET /api/gzil/proposals shows the author as the EVM address. ZilPay holders continue to work as before.