mcphone Market Expansion

v4.7.2 — Market makers, negative futures, and a full hardware repaint

NEW · Market Maker Villager (broker)
- A brand-new villager profession that quotes both a bid and an ask price.
- Cannot be induced with a job-site block — it only spawns naturally in villages (8% per adult villager, max 2 per village, and 80% of villages get only one).
- Every broker keeps its own wallet and inventory, stored in its own NBT (no save migration).
- Spread scales with item rarity: 1.0% – 10.0%. No extra fee — the spread is the cost.
- The broker's name tag shows its current wallet balance; balances settle once per in-game day.

NEW · Futures can now go negative
- Stocks and spot keep the $1 floor; futures no longer have one, so a crash can push the price below zero (like real futures markets).
- Margin is calculated from |notional| × 10%, so it stays valid at negative prices.
- Negative amounts are displayed as -$12.34.

IMPROVED · Rarity fallback
- Without Rarity Core installed, unlisted items are now classified locally into the first 4 tiers only (vanilla rarity, +1 for non-stackable, +1 for damageable).
- With Rarity Core installed, all ratings are requested in bulk on server start via the public API.

FIXED · Computer hardware art & interface alignment
- tower_cpu.png fully repainted: the metal lid now covers the whole socket, engraved "18代强劲CPU". All AMD-related content removed.
- tower_metal_panel.png fully repainted: brushed metal panel with a 9-blade exhaust fan, a bold honeycomb dust mesh reaching all four mounting screws, and a 1200W hub label.
- Monitor console and tower element screens now shift as a whole (frame + content stay aligned via a single reusable layout constant).

REQUIREMENTS
- Minecraft 1.20.1 · Forge 47.4.0+
- MCphone 0.10.2+ — required, install on BOTH client and server. This add-on does not bundle MCphone.
- Rarity Core — optional, enables full 7-tier rarity for modded items.