feat(v0.3): 역할 세분화 + 공지시스템 + 학생대시보드 + 개발자센터

Backend
- User 모델: professor_role/admin_role/nationality/grade 추가
- ProfessorRole enum (전임/겸임/학과장)
- AdminRole enum (교무처/학생처/사무국/기획처/IT센터/입학홍보처/총괄)
- Announcement 모델 (target_audience/type/send_email)
- GET/POST/DELETE /announcements + 이메일 동시 발송
- PATCH /users/{id}/role (역할+세부역할 변경)
- GET /dev/health-check + /dev/stats + /dev/settings
- Alembic 0012

Frontend
- AnnouncementBar: 상단 배너(URGENT) + Footer 슬라이드 알림
- 학생 대시보드: 과제카드 + 공지 + 백분위 + 교수/개발자 전용 링크
- /dev 개발자 센터: 4탭 (시스템현황/사용자CRUD/설정/LLM-RAG)

Author: GabrielJung0727

apps/api/alembic/versions/20260420_0012_roles_announcements.py

@@ -0,0 +1,66 @@
+"""role refinement + announcements table
+
+Revision ID: 0012_roles_announcements
+Revises: 0011_assignments
+Create Date: 2026-04-20 09:00:00
+"""
+
+from collections.abc import Sequence
+
+import sqlalchemy as sa
+from alembic import op
+from sqlalchemy.dialects import postgresql
+
+revision: str = "0012_roles_announcements"
+down_revision: str | None = "0011_assignments"
+branch_labels: str | Sequence[str] | None = None
+depends_on: str | Sequence[str] | None = None
+
+
+def upgrade() -> None:
+    # --- Enums ---
+    for name, values in [
+        ("professor_role_enum", ["FULL_TIME", "ADJUNCT", "DEPT_HEAD"]),
+        ("admin_role_enum", ["ACADEMIC_AFFAIRS", "STUDENT_AFFAIRS", "GENERAL_ADMIN", "PLANNING", "IT_CENTER", "ADMISSIONS", "SUPER_ADMIN"]),
+        ("nationality_enum", ["KOREAN", "INTERNATIONAL"]),
+        ("announcement_target_enum", ["ALL", "STUDENT", "PROFESSOR", "ADMIN", "DEVELOPER"]),
+        ("announcement_type_enum", ["GENERAL", "MAINTENANCE", "URGENT"]),
+    ]:
+        postgresql.ENUM(*values, name=name, create_type=True).create(op.get_bind(), checkfirst=True)
+
+    # --- User model extensions ---
+    op.add_column("users", sa.Column("professor_role", postgresql.ENUM("FULL_TIME", "ADJUNCT", "DEPT_HEAD", name="professor_role_enum", create_type=False), nullable=True))
+    op.add_column("users", sa.Column("admin_role", postgresql.ENUM("ACADEMIC_AFFAIRS", "STUDENT_AFFAIRS", "GENERAL_ADMIN", "PLANNING", "IT_CENTER", "ADMISSIONS", "SUPER_ADMIN", name="admin_role_enum", create_type=False), nullable=True))
+    op.add_column("users", sa.Column("nationality", postgresql.ENUM("KOREAN", "INTERNATIONAL", name="nationality_enum", create_type=False), nullable=True))
+    op.add_column("users", sa.Column("grade", sa.Integer(), nullable=True))
+
+    # --- Announcements ---
+    op.create_table(
+        "announcements",
+        sa.Column("id", postgresql.UUID(as_uuid=True), server_default=sa.text("gen_random_uuid()"), nullable=False),
+        sa.Column("author_id", postgresql.UUID(as_uuid=True), nullable=True),
+        sa.Column("title", sa.String(200), nullable=False),
+        sa.Column("content", sa.Text(), nullable=False),
+        sa.Column("target_audience", postgresql.ENUM("ALL", "STUDENT", "PROFESSOR", "ADMIN", "DEVELOPER", name="announcement_target_enum", create_type=False), nullable=False),
+        sa.Column("announcement_type", postgresql.ENUM("GENERAL", "MAINTENANCE", "URGENT", name="announcement_type_enum", create_type=False), nullable=False),
+        sa.Column("is_active", sa.Boolean(), server_default="true", nullable=False),
+        sa.Column("starts_at", sa.DateTime(timezone=True), server_default=sa.text("now()"), nullable=False),
+        sa.Column("ends_at", sa.DateTime(timezone=True), nullable=True),
+        sa.Column("send_email", sa.Boolean(), server_default="false", nullable=False),
+        sa.Column("created_at", sa.DateTime(timezone=True), server_default=sa.text("now()"), nullable=False),
+        sa.Column("updated_at", sa.DateTime(timezone=True), server_default=sa.text("now()"), nullable=False),
+        sa.PrimaryKeyConstraint("id"),
+        sa.ForeignKeyConstraint(["author_id"], ["users.id"], ondelete="SET NULL"),
+    )
+    op.create_index("ix_announcements_active_target", "announcements", ["is_active", "target_audience"])
+    op.create_index("ix_announcements_type", "announcements", ["announcement_type"])
+
+
+def downgrade() -> None:
+    op.drop_table("announcements")
+    op.drop_column("users", "grade")
+    op.drop_column("users", "nationality")
+    op.drop_column("users", "admin_role")
+    op.drop_column("users", "professor_role")
+    for name in ["announcement_type_enum", "announcement_target_enum", "nationality_enum", "admin_role_enum", "professor_role_enum"]:
+        postgresql.ENUM(name=name).drop(op.get_bind(), checkfirst=True)