[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>

Azaion.AdminApi/BusinessExceptionHandler.cs

@@ -1,4 +1,4 @@
-
+using System.Globalization;
 using Microsoft.AspNetCore.Diagnostics;
 using Microsoft.AspNetCore.Http;
 using Microsoft.Extensions.Logging;
@@ -13,9 +13,12 @@ public class BusinessExceptionHandler(ILogger<BusinessExceptionHandler> logger)
         if (exception is BusinessException ex)
         {
             logger.LogWarning(exception, ex.Message);
-            httpContext.Response.StatusCode = StatusCodes.Status409Conflict;
+            httpContext.Response.StatusCode = MapStatusCode(ex.ExceptionEnum);
             httpContext.Response.ContentType = "application/json";
 
+            if (ex.RetryAfterSeconds is { } retry && retry > 0)
+                httpContext.Response.Headers.RetryAfter = retry.ToString(CultureInfo.InvariantCulture);
+
             var err = JsonConvert.SerializeObject(new
             {
                 ErrorCode = ex.ExceptionEnum,
@@ -42,4 +45,11 @@ public class BusinessExceptionHandler(ILogger<BusinessExceptionHandler> logger)
 
         return false;
     }
-}
+
+    private static int MapStatusCode(ExceptionEnum kind) => kind switch
+    {
+        ExceptionEnum.AccountLocked     => StatusCodes.Status423Locked,
+        ExceptionEnum.LoginRateLimited  => StatusCodes.Status429TooManyRequests,
+        _                               => StatusCodes.Status409Conflict
+    };
+}