📝 docs: audit and correct all ADR statuses and content

Full pass over all 25 ADRs to align documentation with actual
implementation state. Changes by ADR:

README index: completely rewritten — previous table mapped numbers to
wrong titles from 0010 onward.

0008 (BDD Testing): added note that flat features/ structure and godog
CLI invocation are superseded by ADR-0024; framework decision stands.

0009 (Hybrid Testing): renamed from "Combine BDD and Swagger-based
testing" to "BDD Testing with OpenAPI Documentation"; clarified that
the SDK-testing layer was never built and has no open issue.

0013 (OpenAPI/Swagger): removed leftover merge conflict artifact
(=======) and duplicated 60-line block.

0015 (Cobra CLI): fixed status contradiction — body said "Implemented"
while footer said "Proposed". Now Accepted.

0018 (User Management): status Proposed → Accepted; system is fully
implemented (JWT, bcrypt, GORM repos all present).

0019 (PostgreSQL): status Proposed → Accepted (Partial); added warning
that sqlite_repository.go and gorm/driver/sqlite still present contrary
to ADR intent.

0021 (JWT Retention): fixed wrong cross-reference (previously cited
ADR-0009 "Hybrid Testing" as source of JWT multi-secret support); fixed
title number from "10" to "21"; clarified that base JWT is implemented
but the retention cleanup job is not.

0022 (Rate Limiting/Cache): added warning block linking to open Gitea
issue #13; changed all 20 false ✅ implementation checkboxes to ❌.

0023 (Config Hot Reloading): added note that BDD scenarios exist for
this feature but the feature itself is not yet implemented.

0024 (BDD Organization): status Proposed → Accepted; modular domain
structure is fully built.

0025 (BDD Scenario Isolation): status Proposed → Accepted (Partial);
Phase 1 done, Phase 2 blocked on ADR-0022.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

adr/0018-user-management-auth-system.md

@@ -1,7 +1,8 @@
 # 18. User Management and Authentication System
 
 **Date:** 2024-04-06
-**Status:** Proposed
+**Status:** Accepted
+**Implementation Date:** 2026-04-08
 **Authors:** Product Owner
 **Decision Drivers:** Security, User Personalization, Admin Functionality