Add passkeys project: WebAuthn ceremonies, a software authenticator and the one-time-token fallback

Fourth Maven project in the repository. Registration and authentication run end to
end with no browser and no hardware key: VirtualAuthenticator emits real CBOR
attestation objects and real ES256 assertion signatures, and tools/PasskeyCeremony.java
drives the live HTTP endpoints with them.

Profiles cover userVerification REQUIRED, DIRECT attestation, a disallowed origin and
JDBC persistence. Eleven doc chapters and twelve captured transcripts under docs/passkeys
and docs/output/pk-*.txt, all regenerated by passkeys/scripts/run-all.sh.

passkeys/scripts/ceremony.sh

@@ -0,0 +1,11 @@
+#!/usr/bin/env bash
+# The whole thing, end to end: password login, passkey registration, logout, passkey login.
+source "$(dirname "${BASH_SOURCE[0]}")/lib.sh"
+start_app "" > /dev/null
+{
+  header "Registration and authentication ceremonies, driven without a browser"
+  echo "Spring Security 7.1.1, Spring Boot 4.1.1, rpId localhost, default settings."
+  echo "The authenticator is src/main/java/com/ankurm/passkeys/virtual/VirtualAuthenticator.java."
+  ceremony register-and-login
+} 2>&1 | tee "$OUTPUT_DIR/pk-ceremony.txt"
+stop_app