MCA: Romantic Expansion

# Changelog

## v1.0.8 — Love Letter System

### ✉ New: Love Letters

A handwritten letter that can be tucked into books and gifts, waiting for its recipient to discover.

**Writing**
- Craft with paper, book, and pen
- Sneak + right-click to open editor, fill in recipient name and message
- Right-click anytime to read a written letter

**Hiding & Delivery**
- Sneak + right-click while holding any item in offhand to hide the letter inside it
- The host item's appearance remains unchanged—no one can tell it contains a letter
- Only the recipient will have the letter extracted when using the item; other players use it normally, unaware

**Reply & Affection**
- After receiving a letter, click the "Reply" button while reading to write back (on page 2)
- Reply is written on the same letter item—no new item created, preventing duping
- After replying, both parties gain +3 affection each
- Reading without replying does nothing—hearts need answers to grow
- Replies can be written even if the recipient is offline, but affection only increases when both are online
- Once replied, the original sender can also extract the letter from the hidden host item to read the reply

### 🏆 New Achievement

| Achievement | Description |
|-------------|-------------|
| Message in a Bottle | Reply to a love letter—two hearts draw closer |

### 🔧 Technical Changes

- Added `LoveLetterItem` with NBT storage for recipient, sender (incl. UUID), message, and reply
- Reply stored as "page 2" on the same item—no new item created
- Extended `LoveLetterSavePacket` with `isReply` field, reusing the same packet for writing and replying
- Added `LoveLetterReplyTrigger` achievement trigger
- Reading UI displays both original letter and reply; shows "Reply" button if not yet replied
- Hide/extract logic fully preserves reply data
- Extraction permissions: recipient can extract; after reply, original sender can also extract
- Affection gain integrated with existing `AffectionManager` system