[Electric 2.0] Rewrite Quickstart Guide

[KyleAMathews]

Goal

<5 min local setup, <10 min production deploy with claimable resources

Scope

• Focus purely on getting starter running
• Claimable resources flow clearly explained
• Remove/minimize Docker Compose complexity

Current File

/website/docs/quickstart.md (239 lines)

Dependencies

Claimable resources feature must be live in Cloud (see stratovolt#713)

Acceptance Criteria

Developer feedback that setup is < 5 min

Context

Part of Electric 2.0 launch. The quickstart is the first impression - it needs to be fast and delightful.