feat: add per-account flags to block receiving TAO, Alpha, and locked Alpha

[ppolewicz]

Summary

Implements issue #2730: adds the ability for a destination address to block incoming transfers of TAO, staked Alpha, and locked Alpha.

What was added

• 3 new storage maps in pallet-subtensor:

  • BlockReceivingTao<T> — per-account flag to block incoming TAO transfers (only cross-coldkey paths)
  • BlockReceivingAlpha<T> — per-account flag to block incoming staked-Alpha transfers (user-facing entry points only; internal system re-staking is unaffected)
  • BlockReceivingLockedAlpha<T> — per-account flag to block incoming locked-Alpha transfers

• 3 new extrinsics (call indices 139 / 140 / 141):

  • set_block_receiving_tao(enabled: bool)
  • set_block_receiving_alpha(enabled: bool)
  • set_block_receiving_locked_alpha(enabled: bool)

  Each extrinsic uses insert when enabling (saves storage only when true) and remove when disabling (frees storage), which avoids keeping default-false entries in state.

• 3 new error variants:

  • ReceivingTaoBlocked
  • ReceivingAlphaBlocked
  • ReceivingLockedAlphaBlocked

• 3 new events:

  • BlockReceivingTaoSet { account, enabled }
  • BlockReceivingAlphaSet { account, enabled }
  • BlockReceivingLockedAlphaSet { account, enabled }

• Enforcement in existing transfer paths:

  • transition_stake_internal (cross-coldkey TAO transfer) checks BlockReceivingTao — hoisted before any mutations (guard-first pattern)
  • transition_stake_internal (cross-coldkey Alpha re-stake) checks BlockReceivingAlpha — hoisted before any mutations
  • transition_stake_internal same-subnet branch checks BlockReceivingAlpha for cross-coldkey transfers
  • do_add_stake (user-facing stake entry point) checks BlockReceivingAlpha
  • transfer_lock checks BlockReceivingLockedAlpha

• Weight benchmarks added for all three new extrinsics (set_block_receiving_tao, set_block_receiving_alpha, set_block_receiving_locked_alpha).

• 10 unit tests in pallets/subtensor/src/tests/block_receiving.rs covering set/clear, blocking, and allow-after-clear for each flag, plus a new test covering the same-subnet cross-coldkey Alpha block path.

Fixes applied (code review)

• R-1: Hoisted TAO and Alpha block checks before unstake_from_subnet mutation in transition_stake_internal so all guards fire pre-mutation.
• R-2: Added BlockReceivingAlpha check in the same-subnet branch of transition_stake_internal so same-subnet cross-coldkey transfers are also blocked.
• R-4: Added #[benchmark] entries for the three new extrinsics so CI can generate accurate weights.
• R-5: Corrected set_block_receiving_tao docstring to reflect the narrowed check scope (cross-coldkey TAO transfer only).
• R-6: Added test_block_receiving_alpha_prevents_same_subnet_transfer to cover the R-2 fix.

Test plan

• cargo fmt -p pallet-subtensor — no formatting issues
• cargo clippy -p pallet-subtensor --tests — no errors
• cargo test -p pallet-subtensor block_receiving — 10/10 tests pass

[camfairchild]

cACK

[github-actions]

eco-tests changed — indexer review required

This PR modifies files under eco-tests/. and may affect downstream indexing.
cc @evgeny-s — please review manually

Changed files

• eco-tests/Cargo.toml
• eco-tests/src/helpers.rs
• eco-tests/src/lib.rs
• eco-tests/src/mock.rs
• eco-tests/src/tests_taocom_indexer.rs