docs: cross-validate all documentation against codebase, fix 21 inaccuracies

Fact-checked every doc file against actual source code. Key corrections:
- Table count 14→17 (added profiles, agent_groups, agent_group_members)
- Endpoint count 55→68 (counted from router.go)
- Test count 250+→330+ (99 service + 165 handler + 53 frontend + connectors)
- Dashboard views 14→16 pages (counted from web/src/pages/)
- step-ca marked implemented (was "Planned V2") across all docs
- ACME DNS-01 marked implemented (was "planned") in concepts.md
- Removed ADCS as separate planned connector (handled via sub-CA mode)
- Fixed pointer types in connectors.md interface docs (*string, *time.Time)
- Added 3 missing tables to architecture.md ER diagram
- Added 5 missing env vars to README config table
- Updated M11/M12 to ✅ in README roadmap
- Issuer count in quickstart demo data 3→4 (added step-ca)

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

docs/quickstart.md

@@ -214,7 +214,7 @@ The demo comes pre-loaded with realistic data so you can explore certctl's featu
 |----------|-------|---------|
 | Teams | 5 | Platform, Security, Payments, Frontend, Data |
 | Owners | 5 | Alice, Bob, Carol, Dave, Eve |
-| Issuers | 3 | Local Dev CA, Let's Encrypt Staging, DigiCert |
+| Issuers | 4 | Local Dev CA, Let's Encrypt Staging, step-ca Internal, DigiCert (disabled) |
 | Agents | 5 | nginx-prod, nginx-staging, f5-prod, iis-prod, data-agent |
 | Targets | 5 | NGINX (prod/staging/data), F5 LB, IIS |
 | Certificates | 15 | Various statuses: Active, Expiring, Expired, Failed, Wildcard |