[AZ-536] [AZ-537] [AZ-538] Argon2id, login rate limit + lockout, CORS https-only

AZ-536 — replace unsalted SHA-384 password hashing with Argon2id (RFC 9106).
Stored as PHC string with 64 MiB / 3 iter / 1 lane defaults; legacy SHA-384
hashes detected by prefix and lazily re-hashed on next successful login.
Verify uses CryptographicOperations.FixedTimeEquals on both formats.

AZ-537 — add per-IP sliding window rate limit on /login (ASP.NET Core
RateLimiter, 10/60s default — production-tight) plus DB-backed per-account
limit (5/300s) and consecutive-failure lockout (10 / 15 min) on the users
row. Adds a generic audit_events table with INSERT/SELECT-only grants for
the app role so the per-account count is queryable and admins cannot erase
their own forensic trail. BusinessExceptionHandler maps AccountLocked to
423 and LoginRateLimited to 429, both with Retry-After.

AZ-538 — drop the http://admin.azaion.com origin from CORS, gate
UseHsts() + UseHttpsRedirection() to non-Development envs (1y / preload).

Test infra: Npgsql in the e2e project + a DbHelper for direct DB
inspection used by the AZ-536/537 ACs. appsettings.Development.json
raises PerIpPermitLimit to 1000 so the suite (~270 logins from one
container IP) doesn't false-trip the limiter.

Tests: 53 pass + 3 documented skips (per-IP rate limit needs distinct
client IPs; HSTS/HTTPS redirect need ASPNETCORE_ENVIRONMENT=Production).

Code review: PASS_WITH_WARNINGS — 0 Critical, 0 High, 1 Medium, 3 Low.
See _docs/03_implementation/reviews/batch_01_cycle2_review.md.

Closes AZ-530 epic batch 1 of 4.

Co-authored-by: Cursor <cursoragent@cursor.com>

env/db/07_auth_lockout_and_audit.sql

@@ -0,0 +1,26 @@
+-- AZ-537 (Epic AZ-530, CMMC AC.L2-3.1.8): account lockout + audit events.
+-- Adds the per-row state used by UserService.ValidateUser to enforce a 10-failure
+-- consecutive-attempt lockout, plus a generic audit_events table that the per-account
+-- sliding-window rate-limit reads. The audit table is also reused by future security
+-- events (login_success, lockout_release, etc.).
+
+ALTER TABLE public.users
+    ADD COLUMN IF NOT EXISTS failed_login_count int       NOT NULL DEFAULT 0,
+    ADD COLUMN IF NOT EXISTS lockout_until      timestamp NULL;
+
+CREATE TABLE IF NOT EXISTS public.audit_events
+(
+    id          bigserial    PRIMARY KEY,
+    event_type  varchar(64)  NOT NULL,
+    occurred_at timestamp    NOT NULL DEFAULT now(),
+    email       varchar(160) NULL,
+    ip          varchar(64)  NULL,
+    metadata    text         NULL
+);
+
+CREATE INDEX IF NOT EXISTS audit_events_event_type_email_idx
+    ON public.audit_events (event_type, email, occurred_at DESC);
+
+GRANT INSERT, SELECT ON public.audit_events TO azaion_admin;
+GRANT SELECT          ON public.audit_events TO azaion_reader;
+GRANT USAGE, SELECT   ON SEQUENCE public.audit_events_id_seq TO azaion_admin;