feat: refine account management and targeted editing

Add local provider icons, larger compact account rows, the requested column order, and full username display while keeping secrets masked. Replace provider-wide editing with a row-specific editor that preserves sibling accounts, exact limits, live usage counters, and status metadata. Add targeted credential validation, release notices, and regression coverage.

src/renderer/account-ui.ts

@@ -55,6 +55,10 @@ export function isAccountRowSelectionKey(key: string, originatedOnRow: boolean):
   return originatedOnRow && (key === "Enter" || key === " ");
 }
 
+export function resolveAccountUsername(storedUsername: string, checkedEmail?: string): string {
+  return checkedEmail?.trim() || storedUsername.trim() || "—";
+}
+
 export function buildBulkAccountEnabledState(
   currentDisabledProviders: DebridProvider[],
   configuredProviders: DebridProvider[],