Remove BTC purchase mechanism on Scrypt

[TaprootFreak]

Why

On 2026-05-21, buy_crypto #123090 routed a 570'000 EUR -> BTC trade onto Scrypt because Binance had insufficient BTC (Rule 192) and the Binance USDT refill pipeline (Rule 210) is Inactive. We paid 66'487 EUR/BTC on Scrypt vs. Kraken VWAP @ 13:44 UTC of 66'218 EUR/BTC -- a +0.41% premium, ~2'257 EUR more than a hypothetical Kraken-VWAP fill.

In our 6-month history Scrypt BTC/EUR averages a ~0.6% spread over reference, while Scrypt USDT/EUR is ~0.13%. We should not be buying BTC on Scrypt when a cheaper route exists.

The previous attempt (PR #3740) was DB-only -- a future LM rule misconfiguration could re-introduce the same incident. This PR enforces the policy structurally in code so it cannot happen again.

Closes #3739

What

Code (src/subdomains/core/liquidity-management/adapters/actions/scrypt.adapter.ts)

• Remove the sell-if-deficit command from ScryptAdapter (enum entry, command registration, completion check, param validation, the sellIfDeficit method, and its param helpers)
• Remove now-unused constructor dependencies and imports (LiquidityManagementRuleRepository, LiquidityBalanceRepository, BuyCryptoService, PriceCurrency, forwardRef, Inject)
• Add a structural guard in sell() that throws OrderNotProcessableException when tradeAsset === 'BTC' -- fails fast before any balance/price logic
• Add a structural guard in buy() that throws OrderNotProcessableException when targetAssetEntity.dexName === 'BTC' -- same fail-fast semantics

These guards make it impossible for any LM rule misconfiguration to acquire BTC via Scrypt.

Migration (migration/1779381590531-RouteScryptEurViaUsdt.js)

• up(): re-point Rule 313 (Scrypt/EUR redundancy) from Action 261 to Action 233 (Scrypt sell USDT, same action already used by Rule 312 for CHF); then delete Action 261 (Scrypt sell-if-deficit BTC)
• down(): re-insert Action 261 with original params via IDENTITY_INSERT and re-point Rule 313 back to 261
• Rule 314 (Scrypt/BTC withdraw) is kept as cleanup path for any residual BTC sitting on Scrypt

Prerequisite (out of scope, blocks safe deploy)

Rule 210 (Binance/USDT) is Inactive as of 2026-05-21 -- this is exactly why the 2026-05-21 trade fell back to Scrypt in the first place. It must be re-activated before deploying this PR, otherwise large BTC buy_crypto orders will pile up on MissingLiquidity once the Scrypt BTC path is cut. Verify with:

SELECT id, status, [minimal], optimal FROM liquidity_management_rule WHERE id = 210;

Acceptance criteria

• New migration committed in migration/ with a timestamp > 1775745823000 (1779381590531)
• Migration's up() reroutes Rule 313 to Action 233 and deletes Action 261
• Migration's down() restores the previous state
• Code-level structural guards in sell() and buy() prevent BTC acquisition via Scrypt
• sell-if-deficit command fully removed from ScryptAdapter
• Lint, format, build green locally
• Verification queries below produce expected results on DEV
• Draft PR opened against develop on DFXswiss/api
• Linked to Stop buying BTC on Scrypt — route EUR via USDT instead #3739

Verification queries

Before merge

-- Confirm action 261 has no incoming references
SELECT id, system, command, onSuccessId, onFailId
FROM liquidity_management_action
WHERE onSuccessId = 261 OR onFailId = 261;
-- Expected: [] empty

-- Confirm Rule 313 currently points at 261
SELECT id, context, [maximal], redundancyStartActionId
FROM liquidity_management_rule WHERE id = 313;
-- Expected: redundancyStartActionId = 261

After deploy

-- Rule 313 now points at 233
SELECT id, redundancyStartActionId FROM liquidity_management_rule WHERE id = 313;
-- Expected: 233

-- Action 261 is gone
SELECT id FROM liquidity_management_action WHERE id = 261;
-- Expected: [] empty

-- No new Scrypt BTC/EUR trades after migration timestamp
SELECT TOP 5 id, created, symbol, cost, [order]
FROM exchange_tx
WHERE exchange = 'Scrypt' AND symbol = 'BTC/EUR' AND created > '<deploy-date>'
ORDER BY id DESC;
-- Expected: [] empty (any rows mean fallback wasn't fully cut)

End-to-end smoke test on DEV

1. Deposit 1'000 EUR to the DEV Scrypt EUR account
2. Watch liquidity_management_pipeline -- confirm new pipeline targets Rule 313 with action 233 (not 261)
3. Confirm exchange_tx shows a USDT/EUR Scrypt trade, not BTC/EUR
4. Confirm Rule 315 (Scrypt/USDT redundancy) then triggers Action 231 to withdraw USDT to Tron/Binance