Add passkeys (WebAuthn): register from the profile, log in without email

New library dependency: lbuchs/webauthn (^2.2, MIT, zero transitive deps
beyond PHP+OpenSSL+Mbstring, both already required). 'none' attestation --
this only confirms "the same device that registered", not hardware
provenance, the standard trust model for a public site's own passkey login.

Backend
- migrations/010: `passkeys` (one row per registered credential: owner,
  credential_id, public_key, sign_count, label) and `webauthn_challenges`
  (short-lived, single-use, bridging each ceremony's "options" and "verify"
  calls -- user_id set for a registration, null for a login since who's
  signing in isn't known until the credential comes back).
- Config: WEBAUTHN_RP_ID (defaults to APP_URL's host) and WEBAUTHN_RP_NAME.
- PasskeyRepository, WebAuthnChallengeRepository, PasskeyController:
  GET/POST /api/passkeys, POST /api/passkeys/options, DELETE
  /api/passkeys/{id} (all auth), plus the public POST /api/auth/passkey/
  options and /verify for login. Registration always asks for a
  discoverable, user-verified credential -- what makes login usernameless:
  the browser offers whatever passkeys it has for the site, no email first.
- SessionPayload now also exposes `has_passkey` on every user object
  (PasskeyRepository::countForUser() > 0), reused by both the profile page
  and the dismissible notice.
- PasskeyTest: auth guards, options response shape, challenge single-use/
  expiry/purpose/cross-user rules, malformed-input handling, list/remove
  CRUD (seeded rows) -- everything short of a real signature, which isn't
  practical from PHPUnit. 73 tests pass.

Frontend
- lib/webauthn.ts: base64url <-> ArrayBuffer conversion and the two
  ceremonies (registerPasskey, loginWithPasskey), matching the API's wire
  format exactly.
- ProfileView: a Passkeys section -- list with Remove buttons, an "Add a
  passkey" form (label pre-filled from a UA guess).
- LoginView: a "Log in with a passkey" button above the email form, shown
  only when the browser supports WebAuthn.
- PasskeyNotice.vue: dismissible banner across the top of the page
  (`user.has_passkey === false`); dismissal is a week-long localStorage
  timestamp.

Verified against the rebuilt container using a Chrome DevTools Protocol
*virtual authenticator* (real ECDSA signing, no human interaction) end to
end: notice shown -> register a passkey -> notice gone (same page and after
navigating) -> log out -> "Log in with a passkey" with no email typed ->
correct account, notice still gone -> remove the passkey -> notice back ->
dismiss -> stays hidden for ~7 days across pages. Along the way, caught and
fixed a real bug: AuthenticatorData::getCredentialId() returns a raw binary
string, not a ByteBuffer like most of this library's other binary fields --
bin2hex() it directly rather than calling ->getHex().

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

src/Support/Config.php

@@ -19,6 +19,10 @@ final class Config
         public readonly bool $allowRegistration,
         /** Base URL of the frontend, used to build magic links. */
         public readonly string $appUrl,
+        /** WebAuthn relying party ID -- the domain a passkey is bound to. */
+        public readonly string $webauthnRpId,
+        /** WebAuthn relying party display name, shown by the browser/OS passkey prompt. */
+        public readonly string $webauthnRpName,
         public readonly MailConfig $mail,
     ) {
     }
@@ -46,6 +50,12 @@ final class Config
 
         $appUrl = rtrim(self::env('APP_URL', 'http://localhost:5173'), '/');
 
+        // A passkey is bound to a domain (the "relying party ID"), never a full
+        // origin -- defaults to the frontend's host. WebAuthn requires this to
+        // be `localhost` or a real domain served over HTTPS; a LAN IP won't work.
+        $webauthnRpId = self::env('WEBAUTHN_RP_ID') ?? (parse_url($appUrl, PHP_URL_HOST) ?: 'localhost');
+        $webauthnRpName = self::env('WEBAUTHN_RP_NAME', 'Projects');
+
         $mailLogPath = self::env('MAIL_LOG_PATH', $storagePath . '/mail.log');
         if (!self::isAbsolutePath($mailLogPath)) {
             $mailLogPath = $basePath . '/' . ltrim($mailLogPath, '/');
@@ -63,7 +73,17 @@ final class Config
             smtpEncryption: strtolower(self::env('MAIL_SMTP_ENCRYPTION', 'tls')),
         );
 
-        return new self($databasePath, $jwtSecret, $jwtTtl, $displayErrors, $allowRegistration, $appUrl, $mail);
+        return new self(
+            $databasePath,
+            $jwtSecret,
+            $jwtTtl,
+            $displayErrors,
+            $allowRegistration,
+            $appUrl,
+            $webauthnRpId,
+            $webauthnRpName,
+            $mail,
+        );
     }
 
     private static function env(string $key, ?string $default = null): ?string