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>

docker-compose.dev.yml

@@ -0,0 +1,48 @@
+version: "3.8"
+
+services:
+  keycape:
+    build:
+      context: .
+      dockerfile: Dockerfile
+    ports:
+      - "8080:8080"
+    volumes:
+      - ./config/dev-config.yaml:/etc/keycape/config.yaml:ro
+      - ./config/dev-key.pem:/etc/keycape/key.pem:ro
+    environment:
+      - KEYCAPE_CONFIG=/etc/keycape/config.yaml
+    depends_on:
+      - lldap
+      - authelia
+
+  lldap:
+    image: lldap/lldap:stable
+    ports:
+      - "17170:17170"
+      - "3890:3890"
+    environment:
+      - LLDAP_JWT_SECRET=devjwtsecret
+      - LLDAP_LDAP_USER_PASS=adminpassword
+      - LLDAP_LDAP_BASE_DN=dc=netkingdom,dc=local
+    volumes:
+      - lldap_data:/data
+
+  authelia:
+    image: authelia/authelia:latest
+    ports:
+      - "9091:9091"
+    volumes:
+      - ./config/authelia:/config:ro
+    environment:
+      - AUTHELIA_JWT_SECRET=devsecret
+
+  privacyidea:
+    image: khalibre/privacyidea:latest
+    ports:
+      - "5000:80"
+    environment:
+      - PI_ADMIN_PASSWORD=adminpassword
+
+volumes:
+  lldap_data: