fix(lint): resolve remaining ESLint errors (unused vars, any types, react-refresh)

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

frontend/src/lib/certificatesApi.ts

@@ -78,8 +78,9 @@ export const certificatesApi = {
         params: tenantParams(tenantId),
       })
       return data
-    } catch (err: any) {
-      if (err?.response?.status === 404) return null
+    } catch (err: unknown) {
+      const e = err as { response?: { status?: number } }
+      if (e?.response?.status === 404) return null
       throw err
     }
   },

frontend/src/lib/crypto/srp.ts

@@ -29,7 +29,6 @@ const N_HEX =
 const N = BigInt('0x' + N_HEX);
 const g = 2n;
 const N_BYTES = 256; // 2048 bits = 256 bytes
-const N_HEX_LEN = N_BYTES * 2; // 512 hex chars
 
 // ---- Utility Functions ----
 
@@ -39,16 +38,6 @@ function toHex(n: bigint): string {
   return hex;
 }
 
-/** Pad a hex string to N's byte length (512 hex chars) with leading zeros. */
-function padHex(hex: string): string {
-  return hex.padStart(N_HEX_LEN, '0');
-}
-
-/** Convert BigInt to padded hex bytes (for hash inputs involving N-sized values). */
-function bigintToPaddedHex(n: bigint): string {
-  return padHex(toHex(n));
-}
-
 /** Convert hex string to Uint8Array. */
 function hexToBytes(hex: string): Uint8Array {
   const padded = hex.length % 2 === 1 ? '0' + hex : hex;
@@ -93,12 +82,6 @@ function bigintToBytes(n: bigint): Uint8Array {
   return hexToBytes(toHex(n));
 }
 
-/** Hash BigInt values (unpadded, matching srptools int_to_bytes) and return bytes. */
-async function hashBigInt(...values: bigint[]): Promise<Uint8Array> {
-  const inputs = values.map((v) => bigintToBytes(v));
-  return H(...inputs);
-}
-
 /** Pad a BigInt value to N's byte length (256 bytes) matching srptools context.pad(). */
 function padBigInt(n: bigint): Uint8Array {
   const bytes = bigintToBytes(n);