Initial setup: PostgreSQL best practices repository

Skeleton structure for Supabase PostgreSQL experts to add performance
optimization rules. Modeled after Vercel's react-best-practices-build.

Includes:
- Build system (parser, validator, builder)
- Skill manifest and metadata
- Rule templates and writing guidelines
- CI workflow for validation
- Getting started guide for Postgres team

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

GETTING_STARTED.md

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+# Getting Started - Postgres Team
+
+Quick guide to start adding PostgreSQL best practice rules.
+
+## Setup
+
+```bash
+cd packages/postgresql-best-practices-build
+npm install
+```
+
+## Add a Rule
+
+1. Copy template:
+   ```bash
+   cp skills/postgresql-best-practices/rules/_template.md \
+      skills/postgresql-best-practices/rules/query-your-rule.md
+   ```
+
+2. Edit the file with your rule content
+
+3. Validate & build:
+   ```bash
+   cd packages/postgresql-best-practices-build
+   npm run validate
+   npm run build
+   ```
+
+4. Check `skills/postgresql-best-practices/AGENTS.md` for output
+
+## File Prefixes → Sections
+
+| Prefix | Section |
+|--------|---------|
+| `query-` | 1. Query Performance (CRITICAL) |
+| `conn-` | 2. Connection Management (CRITICAL) |
+| `schema-` | 3. Schema Design (HIGH) |
+| `lock-` | 4. Concurrency & Locking (MEDIUM-HIGH) |
+| `security-` | 5. Security & RLS (MEDIUM-HIGH) |
+| `data-` | 6. Data Access Patterns (MEDIUM) |
+| `monitor-` | 7. Monitoring & Diagnostics (LOW-MEDIUM) |
+| `advanced-` | 8. Advanced Features (LOW) |
+
+## Rule Structure
+
+```markdown
+---
+title: Action-Oriented Title
+impact: CRITICAL|HIGH|MEDIUM-HIGH|MEDIUM|LOW-MEDIUM|LOW
+impactDescription: 10x faster queries
+tags: indexes, performance
+---
+
+## Title
+
+Brief explanation.
+
+**Incorrect (why it's bad):**
+```sql
+-- Bad pattern
+```
+
+**Correct (why it's better):**
+```sql
+-- Good pattern
+```
+
+**Supabase Note:** Optional platform guidance.
+
+Reference: [Link](url)
+```
+
+## Key Files
+
+| File | Purpose |
+|------|---------|
+| `rules/_template.md` | Copy this to create new rules |
+| `rules/_contributing.md` | Writing guidelines |
+| `rules/_sections.md` | Section definitions (editable) |
+| `AGENTS.md` | Generated output (don't edit directly) |
+
+## Questions?
+
+- Writing guidelines: `rules/_contributing.md`
+- Full contributor guide: `skills/postgresql-best-practices/README.md`