docs: freeze YuXinGu lexicon, journey, and P1 engineering sources

Establish product language contract, user journey with dual growth engines,
ERD/OpenAPI/Go boundaries, and H5 routes (/profile, /portrait, /relation,
/membership) before P1 implementation.

Co-authored-by: Cursor <cursoragent@cursor.com>

.ai/domain/erd.md

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+# ERD — P1 Schema（冻结草案）
+
+实现时用 migration 落地；列名可微调但**表/聚合关系不得偏离**。  
+类型：Postgres。敏感：生日等属 Profile，需可删账号级联。
+
+---
+
+## Tables
+
+### users
+| column | type | notes |
+|---|---|---|
+| id | uuid PK | |
+| created_at | timestamptz | |
+| status | text | active/deleted |
+
+### device_identities
+| column | type | notes |
+|---|---|---|
+| id | uuid PK | |
+| device_key | text unique | Visitor |
+| user_id | uuid null FK→users | 升级后绑定 |
+
+### profiles
+| column | type | notes |
+|---|---|---|
+| id | uuid PK | |
+| user_id | uuid FK→users | |
+| relation | text | self \| other |
+| display_name | text | |
+| birth_date | date | required P1 |
+| birth_time | time null | optional |
+| birth_place | text null | optional |
+| gender | text null | |
+| relation_type | text null | partner/family/friend… when other |
+| created_at | timestamptz | |
+
+### scales
+| column | type | notes |
+|---|---|---|
+| id | uuid PK | |
+| slug | text unique | |
+| title | text | 探索测试标题 |
+| status | text | published/draft |
+
+### scale_questions
+| column | type | notes |
+|---|---|---|
+| id | uuid PK | |
+| scale_id | uuid FK | |
+| sort | int | |
+| body | jsonb | 题干与选项 |
+
+### scale_results
+| column | type | notes |
+|---|---|---|
+| id | uuid PK | |
+| user_id | uuid FK | |
+| scale_id | uuid FK | |
+| profile_id | uuid FK | |
+| answers | jsonb | |
+| result | jsonb | 探索结果摘要（可公开字段） |
+| created_at | timestamptz | |
+
+### growth_reports
+| column | type | notes |
+|---|---|---|
+| id | uuid PK | |
+| user_id | uuid FK | |
+| profile_id | uuid FK | |
+| type | text | portrait \| relation \| … |
+| summary | jsonb | **基础版**，始终可按规则返回 |
+| detail | jsonb | **深度版**，服务端按权益剥离 |
+| created_at | timestamptz | |
+
+### relation_insights
+| column | type | notes |
+|---|---|---|
+| id | uuid PK | |
+| user_id | uuid FK | |
+| profile_a_id | uuid FK | usually self |
+| profile_b_id | uuid FK | other |
+| summary | jsonb | 对比标签等基础 |
+| report_id | uuid null FK→growth_reports | 深度建议所在报告 |
+| created_at | timestamptz | |
+
+### ask_threads
+| column | type | notes |
+|---|---|---|
+| id | uuid PK | |
+| user_id | uuid FK | |
+| profile_id | uuid FK | 当前解读对象 |
+| created_at | timestamptz | |
+
+### ask_messages
+| column | type | notes |
+|---|---|---|
+| id | uuid PK | |
+| thread_id | uuid FK | |
+| role | text | user \| assistant |
+| content | text | |
+| created_at | timestamptz | |
+
+### memberships
+| column | type | notes |
+|---|---|---|
+| user_id | uuid PK FK→users | |
+| plan | text | month/quarter/year |
+| status | text | active/expired |
+| expires_at | timestamptz | |
+| ask_quota_left | int | |
+
+### orders
+| column | type | notes |
+|---|---|---|
+| id | uuid PK | |
+| user_id | uuid FK | |
+| kind | text | membership \| deep_access |
+| amount_cents | int | |
+| status | text | created/paid/failed |
+| created_at | timestamptz | |
+
+### payments
+| column | type | notes |
+|---|---|---|
+| id | uuid PK | |
+| order_id | uuid FK | |
+| channel | text | mock \| wechat… |
+| status | text | |
+| raw | jsonb null | |
+
+### deep_accesses
+| column | type | notes |
+|---|---|---|
+| id | uuid PK | |
+| user_id | uuid FK | |
+| report_id | uuid FK→growth_reports | |
+| order_id | uuid FK | |
+| created_at | timestamptz | |
+
+### moods（P2 可先建表空用）
+| column | type | notes |
+|---|---|---|
+| id | uuid PK | |
+| user_id | uuid FK | |
+| day | date | |
+| score | int null | |
+| note | text null | |
+
+### memory_items（P3）
+| column | type | notes |
+|---|---|---|
+| id | uuid PK | |
+| user_id | uuid FK | |
+| kind | text | |
+| payload | jsonb | |
+| created_at | timestamptz | |
+
+---
+
+## Relationship sketch
+
+```
+users 1──* profiles
+users 1──* scale_results
+users 1──* growth_reports
+users 1──0..1 memberships
+users 1──* orders 1──* payments
+growth_reports 1──* deep_accesses
+profiles ── relation_insights ── profiles
+users 1──* ask_threads 1──* ask_messages
+```