feat(db): add Phase 3 database migration

- Add review_task table with partial unique index
- Add promotion_request table
- Add skill_star and skill_rating tables
- Add idempotency_record table

server/skillhub-app/src/main/resources/db/migration/V3__phase3_review_social_tables.sql

@@ -0,0 +1,79 @@
+-- V3__phase3_review_social_tables.sql
+-- Phase 3: 审核工作流、提升、评分/收藏、幂等性
+
+-- 审核任务表
+CREATE TABLE review_task (
+    id BIGSERIAL PRIMARY KEY,
+    skill_version_id BIGINT NOT NULL REFERENCES skill_version(id),
+    namespace_id BIGINT NOT NULL REFERENCES namespace(id),
+    status VARCHAR(32) NOT NULL DEFAULT 'PENDING',
+    version INT NOT NULL DEFAULT 1,
+    submitted_by BIGINT NOT NULL REFERENCES user_account(id),
+    reviewed_by BIGINT REFERENCES user_account(id),
+    review_comment TEXT,
+    submitted_at TIMESTAMP NOT NULL DEFAULT CURRENT_TIMESTAMP,
+    reviewed_at TIMESTAMP
+);
+
+CREATE INDEX idx_review_task_namespace_status ON review_task(namespace_id, status);
+CREATE INDEX idx_review_task_submitted_by_status ON review_task(submitted_by, status);
+CREATE UNIQUE INDEX idx_review_task_version_pending ON review_task(skill_version_id) WHERE status = 'PENDING';
+
+-- 提升申请表
+CREATE TABLE promotion_request (
+    id BIGSERIAL PRIMARY KEY,
+    source_skill_id BIGINT NOT NULL REFERENCES skill(id),
+    source_version_id BIGINT NOT NULL REFERENCES skill_version(id),
+    target_namespace_id BIGINT NOT NULL REFERENCES namespace(id),
+    target_skill_id BIGINT REFERENCES skill(id),
+    status VARCHAR(32) NOT NULL DEFAULT 'PENDING',
+    version INT NOT NULL DEFAULT 1,
+    submitted_by BIGINT NOT NULL REFERENCES user_account(id),
+    reviewed_by BIGINT REFERENCES user_account(id),
+    review_comment TEXT,
+    submitted_at TIMESTAMP NOT NULL DEFAULT CURRENT_TIMESTAMP,
+    reviewed_at TIMESTAMP
+);
+
+CREATE INDEX idx_promotion_request_source_skill ON promotion_request(source_skill_id);
+CREATE INDEX idx_promotion_request_status ON promotion_request(status);
+CREATE UNIQUE INDEX idx_promotion_request_version_pending ON promotion_request(source_version_id) WHERE status = 'PENDING';
+
+-- 技能收藏表
+CREATE TABLE skill_star (
+    id BIGSERIAL PRIMARY KEY,
+    skill_id BIGINT NOT NULL REFERENCES skill(id),
+    user_id BIGINT NOT NULL REFERENCES user_account(id),
+    created_at TIMESTAMP NOT NULL DEFAULT CURRENT_TIMESTAMP,
+    UNIQUE(skill_id, user_id)
+);
+
+CREATE INDEX idx_skill_star_user_id ON skill_star(user_id);
+CREATE INDEX idx_skill_star_skill_id ON skill_star(skill_id);
+
+-- 技能评分表
+CREATE TABLE skill_rating (
+    id BIGSERIAL PRIMARY KEY,
+    skill_id BIGINT NOT NULL REFERENCES skill(id),
+    user_id BIGINT NOT NULL REFERENCES user_account(id),
+    score SMALLINT NOT NULL CHECK (score >= 1 AND score <= 5),
+    created_at TIMESTAMP NOT NULL DEFAULT CURRENT_TIMESTAMP,
+    updated_at TIMESTAMP NOT NULL DEFAULT CURRENT_TIMESTAMP,
+    UNIQUE(skill_id, user_id)
+);
+
+CREATE INDEX idx_skill_rating_skill_id ON skill_rating(skill_id);
+
+-- 幂等性记录表
+CREATE TABLE idempotency_record (
+    request_id VARCHAR(64) PRIMARY KEY,
+    resource_type VARCHAR(64) NOT NULL,
+    resource_id BIGINT,
+    status VARCHAR(32) NOT NULL,
+    response_status_code INT,
+    created_at TIMESTAMP NOT NULL DEFAULT CURRENT_TIMESTAMP,
+    expires_at TIMESTAMP NOT NULL
+);
+
+CREATE INDEX idx_idempotency_record_expires_at ON idempotency_record(expires_at);
+CREATE INDEX idx_idempotency_record_status_created ON idempotency_record(status, created_at);