feat(history): badge chat transactions + add a Chat filter

Transactions that carried a chat message (sent or received, messages + contact
requests) now show a "Message" badge in the History tab, and a new "Chat" option
in the type-filter combo shows only those transactions.

Detection reuses what the chat store already tracks: ChatStore gains an inline
chatTxids() returning the set of on-chain txids that carried a chat message; the
tab builds it once per frame (cheap — O(chat messages)) and tests txid membership
for the badge and the filter. Empty when chat is disabled or the wallet has no
chat identity. Both variants populate the chat store before this tab renders, so
the same code serves full-node and lite with no separate handling.

The "Message" badge reuses the stacked top-pill slot (chat txs are send/receive,
not the autoshield "shield" type, so it and the "Shielded" badge are mutually
exclusive; chat takes precedence) in a distinct Secondary() colour. Guards the
summary-card accent idx_map so the new filter value (4) can't index it OOB.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

res/lang/zh.json

@@ -167,6 +167,7 @@
     "chat_export_done": "会话已导出",
     "chat_export_failed": "无法写入导出文件。",
     "chat_export_warn": "将解密后的消息保存为纯文本。请妥善保管该文件。",
+    "chat_filter": "聊天",
     "chat_hidden_toast": "会话已隐藏——收到新消息后会重新显示",
     "chat_hide": "隐藏",
     "chat_hide_hidden": "收起已隐藏",
@@ -1526,6 +1527,7 @@
     "tt_website": "打开 DragonX 网站",
     "tt_window_opacity": "背景不透明度（越低 = 桌面透过窗口可见）",
     "tt_wizard": "重新运行初始设置向导\\n守护进程将被重启",
+    "tx_chat_badge": "消息",
     "tx_confirmations": "%d 次确认",
     "tx_details_title": "交易详情",
     "tx_from_address": "发送地址：",