feat(im): add ambient mention mode for group chats

[SBeator]

中文说明

背景

这个改动主要解决「一个群里有多个 AI，但默认聊天对象通常是主 AI」时的误响应问题。

现在如果主 AI 配置成 never（不需要 @ 也响应），它会把群里的已经明确 at 其他机器人的消息都当成自己该接的消息。这个模式解决这个问题：默认情况下有单主 AI 的群，这个群里如果临时需要多个 AI 协作时，避免主 AI 接收大量噪声的问题：用户或者某个 AI 明明已经 @ 了另一个 AI / 成员，主 AI 仍然会跟着响应，导致委托关系不清晰，也会打断 AI 之间的接力协作。

新增模式

新增第 4 种群聊 @ 策略：ambient。

它的语义是：默认像 never 一样，不需要 @ 也可以响应；但如果这条消息明确 @ 了其他具体成员（人或 bot），并且没有 @ 当前 bot，则当前 bot 主动让位、保持沉默。

具体行为：

• 没有 @ 任何人：响应
• @ 当前 bot：响应
• @ 其他具体成员、但没 @ 当前 bot：不响应，让位
• @ 所有人：不视为交给某个具体成员，仍可响应
• 原有 never 语义不变，仍然是无条件免 @ 响应

改动范围

• 配置类型与解析支持 ambient
• dashboard 默认设置下拉增加新选项与中英文文案
• daemon 路由门控在 3 处接入 mentionsAnotherMember() 判定
• 新增/补充单测覆盖 ambient 的核心路由行为

验证

• pnpm build
• pnpm vitest run test/event-dispatcher.test.ts test/card-prefs-store.test.ts test/bot-registry-grant.test.ts

本地定向验证 162 条测试通过。

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Summary

This adds a new ambient regular group mention mode alongside the existing always, topic, and never modes.

ambient is intended for groups with a default primary AI where most unmentioned messages should go to that primary AI, while still allowing multi-agent collaboration by explicitly @mentioning another AI or person. In that case, the primary AI should yield instead of also responding.

Behavior:

• unmentioned message -> answer, like never
• message @mentions this bot -> answer
• message @mentions another specific member but not this bot -> stay quiet
• @all is not treated as a redirect, so it still answers
• existing never behavior is unchanged and remains unconditional

Why

In a group with multiple AI bots, the current never mode works well for making a primary AI respond by default. But during AI-to-AI collaboration, users often explicitly @mention another AI. Today the primary AI still responds because never treats every non-self-mentioned group message as eligible. That creates noisy duplicate responses and makes delegation harder.

ambient preserves the default-oncall style experience while adding a small redirect carve-out when the user has clearly addressed someone else.

Changes

• Add ambient to bot config parsing and card preference persistence.
• Add mentionsAnotherMember() and apply it to the top-level gate and shared-topic fold-back paths.
• Add dashboard dropdown support and zh/en labels.
• Add focused tests for the mention predicate and ambient routing behavior.

Validation

• pnpm build
• pnpm vitest run test/event-dispatcher.test.ts test/card-prefs-store.test.ts test/bot-registry-grant.test.ts

Local validation passed with 162 focused tests.

[deepcoldy]

Code-owner 审批通过。

经两轮 review（Claude）+ 一轮独立二次 review（Codex）：

• 核心修复已就位：mentionsAnotherMember 使用 mentionOpenId(m)，兼容 WS 对象形态与 REST cli_ 字符串形态；
• 测试覆盖完整：predicate 单测 + 字符串形态回归 + ambient 三处免@决策点（顶层 gate / shared seeding / alias fold-back）端到端 gating 用例（含让位 carve-out，经变异测试验证非空跑）；
• tsc 净、event-dispatcher 167 测试全过、MERGEABLE。