비밀번호 정책 및 변경 강제 적용 기능 추가:

- 비밀번호 규칙 클라이언트 검증 JS/SASS 추가
- 세션 기반 비밀번호 변경 강제 Interceptor 구현 (`PasswordChangeEnforcementInterceptor`)
- URL 리팩토링 및 엔드포인트 변경 (`/password/*`)
- 비밀번호 유효성 검사 공통화 (`PasswordRuleValidator`)
- Logback ERROR 전용 파일 로그 추가

src/main/resources/static/css/main.css

@@ -7571,6 +7571,69 @@ button.djb-comment-submit:disabled {
   font-size: 13px;
 }
 
+.password-policy-checklist {
+  list-style: none;
+  padding: 0;
+  margin: 12px 0 0 0;
+}
+.password-policy-checklist li {
+  display: flex;
+  align-items: center;
+  gap: 8px;
+  font-size: 15px;
+  line-height: 20px;
+  margin-bottom: 6px;
+  transition: color 0.15s ease;
+}
+.password-policy-checklist li:last-child {
+  margin-bottom: 0;
+}
+.password-policy-checklist li .policy-icon {
+  display: inline-flex;
+  align-items: center;
+  justify-content: center;
+  width: 18px;
+  height: 18px;
+  flex-shrink: 0;
+  font-size: 13px;
+  font-weight: 700;
+  line-height: 1;
+}
+.password-policy-checklist li .policy-icon::before {
+  content: "•";
+}
+.password-policy-checklist li.is-idle {
+  color: #888;
+}
+.password-policy-checklist li.is-idle .policy-icon {
+  color: #b5b5b5;
+}
+.password-policy-checklist li.is-pass {
+  color: #1a8f4c;
+}
+.password-policy-checklist li.is-pass .policy-icon {
+  color: #1a8f4c;
+}
+.password-policy-checklist li.is-pass .policy-icon::before {
+  content: "✔";
+}
+.password-policy-checklist li.is-fail {
+  color: #d63a3a;
+}
+.password-policy-checklist li.is-fail .policy-icon {
+  color: #d63a3a;
+}
+.password-policy-checklist li.is-fail .policy-icon::before {
+  content: "✖";
+}
+
+.password-policy-note {
+  margin: 10px 0 0 0;
+  font-size: 14px;
+  line-height: 18px;
+  color: #888;
+}
+
 .hero-carousel-section {
   position: relative;
   width: 100%;