FEL-623: ship passkey-first identity platform 0.6.0.0

[codeyousef]

Summary

Ships the breaking Aether 0.6.0.0 passkey-first identity platform tracked by FEL-623 and its child issues.

This replaces the old password/JWT-based aether-auth surface with storage-neutral KMP identity contracts, WebAuthn and recovery flows, organization RBAC, RFC 8628 device authorization, service identities, optional PostgreSQL/Firestore/Summon/OIDC/SAML/SCIM modules, and Seen FEL-634 consumer fixtures.

Why

The previous authentication package coupled identity to legacy passwords, sessions, global permissions, and ORM APIs. The new design makes passkeys primary, keeps organization authority tenant-scoped, and provides the same protocol and storage contracts across JVM, wasmJs, and wasmWasi where the runtime supports the required capabilities.

Breaking impact

• Releases as 0.6.0.0; there are no password compatibility wrappers or automatic legacy identity migration.
• Removes the legacy aether-auth password, JWT, ActiveRecord session, group, and permission APIs.
• Applications must create new UUID identities and enroll a passkey or use an explicit recovery path.
• Generic aether-core authentication/session facilities remain available for unrelated applications, but are not used by the identity platform.
• The migration guide, threat model, deployment rules, storage resources, and updated examples live under docs/.

Verification

• ./gradlew verifyExpectedSourceTasks check --dependency-verification=strict --no-daemon --stacktrace
• npm run typecheck --prefix e2e-tests
• npm test --prefix e2e-tests
• cmake -S aether-identity-wasi-host -B build/identity-wasi-host
• cmake --build build/identity-wasi-host
• ctest --test-dir build/identity-wasi-host --output-on-failure

Release gates

Merging this PR runs the repository verification workflow. Maven Central publication remains deliberately manual and fail-closed until the real wasmWasi component gate is present and the required hardware-passkey smoke-test and independent adversarial-review evidence have been supplied.

Linear: FEL-623, FEL-625, FEL-627, FEL-628, FEL-626