security: switch default hashing to Argon2id, fix tests
- hashPassword now uses Argon2id (memory-hard, GPU-resistant) via hash-wasm
- verifyPassword checks both Argon2id and bcrypt
- Legacy hashes (bcrypt, argon2, md5, sha1, sha256, sha512, combined, salted)
auto-migrate to Argon2id on successful login
- Updated all password tests to expect Argon2id format
- Register validation: min 12 chars, max 128, upper+lower+digit+special required
- Username restricted to [A-Za-z0-9_-], reserved names blocked
- Disposable email domains blocked
- Fixed parameter names for hash-wasm argon2id API (memorySize, iterations, parallelism, hashLength)