feat: support fee-token IGP enforcement in agents

[paulbalaji]

Summary

Adds the Rust agent side of exact non-native IGP fee-token support on top of #8892.

Changes:

• extends InterchainGasPayment with fee_token and token-aware encoding/DB keys
• indexes GasPaymentWithFeeToken in Ethereum/Tron while preserving legacy fallback behavior
• adds scraper schema migration/storage for fee_token
• enforces relayer gas payment policies by (messageId, destination, feeToken)
• adds fail-closed config validation: non-zero feeToken requires origins with explicit latest/token-aware IGP metadata
• updates SDK agent config schema for igpVersion and feeToken

Stack

Stacked on #8892, which adds/emits the token-aware IGP event. This PR should be reviewed after the contract/event PR.

Scraper Migration Notes

Adds scraper migration m20260611_000008_add_gas_payment_fee_token.

Migration up():

• adds non-null gas_payment.fee_token as Address/bytea
• backfills existing rows to native token with 0x0000000000000000000000000000000000000000
• removes the temporary default after backfill
• adds gas_payment_msg_id_fee_token_idx on (msg_id, fee_token)
• recreates total_gas_payment grouped by (msg_id, fee_token) instead of only msg_id

Rollout notes:

• apply the scraper DB migration before or with the scraper binary that writes fee_token
• no manual backfill is needed for existing rows; they become native-token rows
• downstream readers of total_gas_payment should expect one row per (msg_id, fee_token), not one row per msg_id
• exact non-native fee-token enforcement still requires origins to be configured as latest/token-aware IGPs, so legacy origins fail closed for non-zero feeToken

Rollback notes:

• down() recreates the legacy view only if all rows are native-token rows
• rollback fails closed if any non-native fee_token rows exist, because dropping the column would merge distinct token amounts into one aggregate and corrupt totals
• rolling back after non-native rows exist requires an explicit data plan or DB restore, not a blind migration rollback

Validation

• cd rust/main && cargo test -p relayer fee_token_policy
• cd rust/main && cargo test -p hyperlane-base db_native_token_key_reads_legacy_total_after_new_native_payment
• cd rust/main && cargo check -p hyperlane-base -p relayer -p scraper
• cd rust/main && cargo clippy -p hyperlane-base -p relayer -p scraper -- -D warnings
• pnpm -C typescript/sdk exec mocha --config .mocharc.json ./src/metadata/agentConfig.test.ts --exit
• git diff --check

[paulbalaji]

Review pass across the stacked PRs (#8892 + #8893). Findings below; I am going to remediate these next.

#8892 Solidity:

• Low/test gap: native payments emit GasPaymentWithFeeToken(..., address(0), ...) through _payForGas, but the native payForGas test only expects legacy GasPayment. Add a native-path expectation so the zero-address sentinel is pinned.

#8893 agents/scraper/SDK:

• Medium: message_view still aggregates gas_payment by msg_id only, so mixed native/ERC20 fee-token payments can produce ambiguous num_payments, total_payment, and total_gas_amount values across denominations. The new migration updates total_gas_payment, but not message_view.
• Medium/Low: scraper migration leaves the temporary fee_token default in place. The modify_column(...not_null()) call does not drop the default; use explicit ALTER TABLE "gas_payment" ALTER COLUMN "fee_token" DROP DEFAULT and remove the redundant alter.
• Medium/test-hardening: EVM/Tron event dedup is transaction-wide. Current Solidity invariant makes this safe today because latest IGP emits legacy + token-aware events together, but parser tests should pin legacy-only, native latest, ERC20 latest, and multi-payment behavior; field-level companion matching would be more robust.
• Process: feat: support fee-token IGP enforcement in agents #8893 is stacked on a slash-containing base branch, and the main test/rust pull_request branch globs are *, so full CI is not gating this stacked PR. Need manual focused validation before relying on green checks.
• Low: SDK changeset wording overstates TypeScript schema enforcement; Rust enforces latest IGP metadata, while Zod only accepts the optional fields. Also IgpVersion should be root-exported if public.

[paulbalaji]

Remediations pushed.

#8892:

• Pushed 22d7d08e5c (test: assert native fee-token gas payment events) adding native GasPaymentWithFeeToken(..., address(0), ...) expectations for direct payForGas and native postDispatch.

#8893:

• Rebased onto updated feat: emit fee-token gas payment events #8892 and pushed 1242c6299e (fix: harden fee-token gas payment indexing).
• Scraper migration now explicitly drops the temporary fee_token backfill default and recreates message_view with native-only legacy gas totals; down migration drops/restores the dependent view before dropping fee_token.
• EVM/Tron indexers now dedup only matching token-aware/legacy companion events by tx + message/payment fields, not by whole transaction; both packages have same-tx unmatched-legacy regression tests.
• Added malformed feeToken parser coverage.
• Exported IgpVersion from the SDK root and corrected the changeset wording.
• Updated test and rust workflow PR branch globs to **, so slash-containing stacked base branches trigger full CI.

Local validation passed:

• forge test --match-contract InterchainGasPaymasterTest --match-test 'testPayForGas|testPostDispatch_defaultGasLimit'
• cargo test -p migration --lib
• cargo test -p relayer fee_token_policy --lib
• cargo test -p hyperlane-ethereum field_level_dedup_keeps_unmatched_legacy_payments_in_same_tx --lib
• cargo test -p hyperlane-tron field_level_dedup_keeps_unmatched_legacy_payments_in_same_tx --lib
• pnpm --dir typescript/sdk exec mocha --config .mocharc.json './src/metadata/agentConfig.test.ts' --exit
• git diff --check
• cargo fmt --check

CI state at last check: #8892 was green except one rust-e2e-tests / e2e-matrix (sealevel) job still in progress; #8893 full GitHub workflows were triggered and still in progress after the glob fix.