auto-claude: subtask-1-2 - Apply migration to Supabase database

Created migration application scripts and comprehensive documentation:
- scripts/apply-migration.js - Automated migration (requires service role key)
- scripts/verify-migration.js - Table verification script
- scripts/test-env.js - Environment diagnostics
- supabase/APPLY_MIGRATION.md - Comprehensive migration guide
- supabase/MIGRATION_INSTRUCTIONS.md - Quick reference

Manual application via Supabase dashboard is recommended approach.

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

supabase/MIGRATION_INSTRUCTIONS.md

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+# Supabase Migration Instructions
+
+## Apply Migration: Create rate_limits Table
+
+### Quick Steps
+
+1. **Open Supabase SQL Editor**
+   - Go to: https://app.supabase.com/project/mxadgucxhmstlzsbgmoz/sql
+
+2. **Copy Migration SQL**
+   - Open: `supabase/migrations/20260125_create_rate_limits_table.sql`
+   - Copy all contents (Ctrl+A, Ctrl+C)
+
+3. **Execute Migration**
+   - Paste the SQL into the Supabase SQL editor
+   - Click the "Run" button (or press Ctrl+Enter)
+   - Wait for "Success. No rows returned" message
+
+4. **Verify Table Creation**
+   - Go to Table Editor: https://app.supabase.com/project/mxadgucxhmstlzsbgmoz/editor
+   - Look for "rate_limits" table in the list
+   - Click on it to verify the schema
+
+### Expected Table Schema
+
+The `rate_limits` table should have:
+
+| Column | Type | Description |
+|--------|------|-------------|
+| identifier | TEXT | Client identifier (IP address) |
+| count | INTEGER | Number of requests in window |
+| window_start | TIMESTAMPTZ | Start of rate limit window |
+| created_at | TIMESTAMPTZ | When record was created |
+| updated_at | TIMESTAMPTZ | When record was last updated |
+
+**Primary Key:** (identifier, window_start)
+
+**Indexes:**
+- `idx_rate_limits_identifier_window` on (identifier, window_start DESC)
+- `idx_rate_limits_window_start` on (window_start)
+
+### Alternative: Using Supabase CLI (if available)
+
+If you have Supabase CLI installed:
+
+```bash
+supabase db push
+```
+
+Or apply the specific migration:
+
+```bash
+supabase migration up
+```
+
+### Verification Query
+
+Run this query in the SQL editor to verify the table exists:
+
+```sql
+SELECT
+  table_name,
+  column_name,
+  data_type,
+  is_nullable
+FROM information_schema.columns
+WHERE table_name = 'rate_limits'
+ORDER BY ordinal_position;
+```
+
+You should see all 5 columns listed.
+
+### Troubleshooting
+
+**Error: "relation already exists"**
+- The table already exists. You can verify by checking Table Editor.
+
+**Error: "permission denied"**
+- Make sure you're logged into the correct Supabase project.
+- Verify you have admin/owner access to the project.
+
+**Table not appearing in Table Editor**
+- Refresh the page (F5)
+- Check the SQL editor for any error messages
+- Verify the SQL was executed successfully