fix biometric, tx dedup, loading crash; add flush cache; remove monero startup from evm init

- biometric-helper: use .deviceOwnerAuthentication so passcode can
  unlock Touch ID when biometrics are locked out
- get-transaction-history: dedup transfers by hash+category+contract
  instead of hash alone (was dropping token transfers sharing a tx hash)
- evm-wallet.svelte.ts: add missing loading  declaration (caused
  ReferenceError on createWallet); add flushTxCache method; comment out
  monero startup from evm init to speed up loading
- get-history.ts: remove dead caching logic (now handled by sync engine);
  import getTransactionHistory from alchemy directly
- backend RPC + settings UI: add flushTxCache to clear tx cache tables

apps/desktop/src/lib/electrobun.ts

@@ -145,6 +145,10 @@ type RPC = {
 				params: { address: string; chainid: string }
 				response: void
 			}
+			flushTxCache: {
+				params: {}
+				response: void
+			}
 			fetchTokenBalances: {
 				params: {
 					address: string