[Price Compare] Step 7: Update MJML email template with all sections

[frankieboxx]

Step 7 — MJML Email Template Update

Redesign the email template to include all new analysis sections.

Sections (in order):

1. Header — "Dnevni izvještaj cijena — Atrium" + date
2. Sažetak — Total items matched, total potential savings €, top saving
3. Top 10 najskupljih — Table: rank, product, total €, alternative, potential saving
4. Tjedni trend — Table: product, last week avg, this week avg, ↑↓ %
5. Kategorije — Table: category, total €, % share
6. Detaljna usporedba — Full comparison table (fixed unit prices)
7. Footer — Generated timestamp

Design:

• Brand color: #1a73e8
• Green for savings, red for price increases
• Responsive MJML, tested in Gmail/Outlook

File: scripts/price_compare.py (MJML template section)
Depends on: #75, #76, #77 (Steps 4-6)
Priority: P2