feat: implement T22, T18, T23 — dev stack, profile tests, server binary

- T22: docker-compose.dev.yml dev stack, Dockerfile, root Makefile
- T18: Profile test suite (Scenario A) — 8 integration tests with real handlers
- T23: Server binary wiring all components, config validation, /healthz
- Config: ValidateConfig with startup validation

14 test packages pass.

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

config/dev-config.yaml

@@ -0,0 +1,27 @@
+issuer: "http://localhost:8080"
+port: 8080
+tokenLifetime: "15m"
+privateKeyPem: "/etc/keycape/key.pem"
+environment: "dev"
+lldap:
+  url: "ldap://lldap:3890"
+  bindDN: "cn=admin,ou=people,dc=netkingdom,dc=local"
+  bindPW: "adminpassword"
+  baseDN: "dc=netkingdom,dc=local"
+authelia:
+  baseURL: "http://authelia:9091"
+  clientId: "keycape"
+  clientSecret: "changeme"
+  redirectURI: "http://localhost:8080/authorize/callback"
+privacyidea:
+  baseURL: "http://privacyidea:80"
+  adminToken: "changeme"
+  realm: "netkingdom"
+clients:
+  - clientId: "demo-app"
+    displayName: "Demo Application"
+    redirectUris:
+      - "http://localhost:3000/callback"
+    allowedScopes: ["openid", "profile", "email", "groups"]
+    grantTypes: ["authorization_code"]
+    clientType: "public"