Fix all 45 audited bugs from bug-fixes.md

Verified every finding against the code, then fixed correctness (redirects,
advancement reset, duplicate heats, high-jump attempt entry, placement
ranking with tie handling, delete-dependency 500s), security (secrets out of
config, config-driven admin seed, login lockout, role authorization with
school scoping, heat-time IDOR, forwarded headers, last-admin guards),
schema integrity (nullable+filtered ExistingStudentId, unique indexes for
rounds/heats/bar heights via SchemaIntegrityFixes migration), performance
(N+1 removal in high jump/reports/standings/dashboard, SQL-side student
paging), and hygiene (duplicate notifications, auto-dismiss scope, local
bootstrap-icons, orphaned files, test-data.sql tournament creation).

FluentValidation is now registered; AutoMapper bumped to 14.0.0 (advisory
fully patched only in licence-changed 15.1.1 — documented). 11 new tests;
63/63 passing. Credential rotation and deploy-time DB_CONNECTION_STRING are
required manual follow-ups, documented in bug-fixes.md.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

src/SportsDivision.Application/DTOs/PlacementPointConfigDto.cs

@@ -1,2 +1,3 @@
 namespace SportsDivision.Application.DTOs;
 public class PlacementPointConfigDto { public int PlacementPointConfigId { get; set; } public int Placement { get; set; } public int Points { get; set; } }
+public class PlacementPointConfigCreateDto { public int Placement { get; set; } public int Points { get; set; } }