[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.Common/Database/AzaionDb.cs

@@ -8,4 +8,5 @@ public class AzaionDb(DataOptions dataOptions) : DataConnection(dataOptions)
 {
     public ITable<User>            Users             => this.GetTable<User>();
     public ITable<DetectionClass>  DetectionClasses  => this.GetTable<DetectionClass>();
+    public ITable<AuditEvent>      AuditEvents       => this.GetTable<AuditEvent>();
 }

Azaion.Common/Database/AzaionDbShemaHolder.cs

@@ -42,6 +42,12 @@ public static class AzaionDbSchemaHolder
                 .IsPrimaryKey()
                 .IsIdentity();
 
+        builder.Entity<AuditEvent>()
+            .HasTableName("audit_events")
+            .Property(x => x.Id)
+                .IsPrimaryKey()
+                .IsIdentity();
+
         builder.Build();
     }
 }