docs: add Development Setup section to README

[Copilot]

The README documented production Docker deployment but omitted local development setup despite the project having comprehensive dev infrastructure (Makefile, pytest, pre-commit hooks, uv tooling).

Added Development Setup Section

• Prerequisites: Python 3.14+, uv, PostgreSQL 14+, make
• Initial Setup: Clone, start local PostgreSQL, configure environment, install dependencies, run migrations
• Testing: Run test suite with coverage using make test or uv run pytest
• Linting: Pre-commit hooks with ruff, mypy, and file checks via make lint
• Local Server: Development server instructions with make run-server
• Migrations: Creating and applying Alembic migrations
• Docker Build: Local image builds with make docker-build
• Development Workflow: Branch creation, testing, committing with pre-commit hooks
• Project Structure: Directory layout overview
• Makefile Reference: Table of all available commands

Section positioned after Troubleshooting, follows existing README style with emojis and code examples.

Original prompt

Suggest an update to the README.md file that includes some important part of the project that has not yet been documented.

---

💬 We'd love your input! Share your thoughts on Copilot coding agent in our 2 minute survey.