Document /run-migrate/ endpoint and unreliable auto-migrations

Flatlogic doesn't always run migrations on Pull Latest. Added note
about using /run-migrate/ to fix "Unknown column" errors after deploy.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

CLAUDE.md

@@ -126,6 +126,7 @@ python manage.py check                      # System check
 | `/payroll/payslip/<pk>/` | `payslip_detail` | Admin: view completed payslip |
 | `/receipts/create/` | `create_receipt` | Staff: expense receipt with line items |
 | `/import-data/` | `import_data` | Setup: run import command from browser |
+| `/run-migrate/` | `run_migrate` | Setup: run pending DB migrations from browser |
 
 ## Frontend Design Conventions
 - **CSS variables** in `static/css/custom.css` `:root` — always use `var(--name)`:
@@ -164,7 +165,7 @@ PROJECT_DESCRIPTION, PROJECT_IMAGE_URL  # Flatlogic branding
 - **Branches**: `ai-dev` = development (Flatlogic AI + Claude Code). `master` = deploy target.
 - **Workflow**: Push to `ai-dev` → Flatlogic auto-detects → "Pull Latest" → app rebuilds (~5 min)
 - **Deploy from Git** (Settings): Full rebuild from `master` — use for production
-- **Migrations**: Run automatically during Flatlogic rebuild
+- **Migrations**: Sometimes run automatically during rebuild, but NOT always reliable. If you get "Unknown column" errors after pulling latest, visit `/run-migrate/` in the browser to apply pending migrations manually. This endpoint runs `python manage.py migrate` on the production MySQL database.
 - **Never edit `ai-dev` directly on GitHub** — Flatlogic pushes overwrite it
 - **Gemini gotcha**: Flatlogic's Gemini AI reads `__pycache__/*.pyc` and gets confused. Tell it: "Do NOT read .pyc files. Only work with .py source files."
 - **Sequential workflow**: Don't edit in Flatlogic and Claude Code at the same time