docs: update PHASE_5_DEVELOPER_SETUP.md — stale setup.sh references throughout

[mrveiss]

Problem

docs/developer/PHASE_5_DEVELOPER_SETUP.md still references the deleted setup.sh extensively (6+ occurrences). The entire Quick Start and Step 2/Step 3 sections are based on bash setup.sh --full/--minimal/--distributed which no longer exists.

Locations

• Line 18: bash setup.sh --full
• Line 124: # You should see: setup.sh, scripts/, docs/, etc.
• Lines 129-154: Three setup modes (--full, --minimal, --distributed)
• Lines 156+: Describes setup phases that no longer apply

Suggested Fix

Rewrite to document the three actual deployment paths:

1. install.sh + Setup Wizard (bare-metal)
2. docker compose up -d (Docker)
3. Ansible fleet deployment from .19

Discovered During

Code review of #2420 session.

[mrveiss]

Merged in PR #2454. Updated PHASE_5_DEVELOPER_SETUP.md with current install paths.