chore: eliminate all ESLint warnings, enforce --max-warnings 0 (#5)

Behavior-preserving lint cleanup of the 30 pre-existing warnings, fixed
by category (no blanket suppression):
- no-explicit-any (19): precise local types / ApiPromise for Substrate
  dynamic queries + 'as unknown as' casts (same pattern as TokensCard).
- no-console (4): dev-gated (import.meta.env.DEV) / warn; main.tsx prod
  console-suppression kept with a scoped documented disable.
- no-non-null-assertion (4): replaced '!' with explicit guards reusing
  the existing fallback/return paths.
- react-hooks/exhaustive-deps (3): missing dep is 't' (i18n) — adding it
  would re-fire blockchain fetches on language change; kept deps with a
  documented intentional disable.

Tighten the lint gate from --max-warnings 30 to 0 so no new warnings can
land. Verified: tsc 0 errors, eslint --max-warnings 0 clean, vite build ok.

src/main.tsx

@@ -9,13 +9,16 @@ import { LanguageProvider } from './i18n';
 import App from './App';
 import './index.css';
 
-// Suppress console logs in production
+// Suppress non-critical console output in production. This is the one place
+// that legitimately overrides console.log/debug/info — warn/error are kept for
+// critical issues. The no-console rule is disabled only for these assignments.
 if (import.meta.env.PROD) {
   const noop = () => {};
-  console.log = noop;
-  console.debug = noop;
-  console.info = noop;
-  // Keep console.warn and console.error for critical issues
+  const suppressed: Array<'log' | 'debug' | 'info'> = ['log', 'debug', 'info'];
+  for (const method of suppressed) {
+    // eslint-disable-next-line no-console
+    console[method] = noop;
+  }
 }
 
 // Initialize Telegram WebApp