feat(platform): enrich group metadata across adapters

[Soulter]

Motivation

Group metadata support was inconsistent across platform adapters. Many incoming group messages only exposed an ID, while AstrMessageEvent.get_group() either returned no data or platform-specific partial results. This prevented conversation aliases and plugins from reliably displaying human-readable group information.

Modifications / 改动点

• Add Group.member_count and make the base get_group() return inbound or ID-only metadata as a safe fallback.

• Attach available group names to incoming messages without adding network requests to the hot path.

• Enrich group name, avatar, owner, administrators, member count, and members where supported by aiocqhttp, QQ Official, Lark, Discord, Telegram, Slack, Mattermost, KOOK, LINE, Misskey, and Satori.

• Preserve basic metadata when optional platform APIs fail, and avoid exposing incomplete member lists as complete results.

• Resolve Lark private-message sender names through Contact v3 with bounded positive and negative caches, a five-second lookup timeout, and documented Contact scopes.

• Use guild-channel display names for Discord group sessions.

• Use group-topic display names for Telegram forum topics when the Bot API has exposed the topic name through creation, edit, or root service messages. Unknown topic names safely fall back to the parent group name because the Bot API has no topic-by-ID lookup.

• Add adapter and fallback regression coverage without introducing new dependencies.

• This is NOT a breaking change. / 这不是一个破坏性变更。

Screenshots or Test Results / 运行截图或测试结果

Verification commands:

git diff --name-only origin/master...HEAD | rg "^tests/.*[.]py$" | xargs uv run pytest -q
uv run ruff format --check .
uv run ruff check .
git diff --check origin/master...HEAD

Results:

• 225 affected tests passed.
• Ruff format and lint checks passed for the full repository.
• Diff whitespace validation passed.

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Checklist / 检查清单

• 😊 This feature was discussed with the project maintainer before implementation.
• 👀 The changes are covered by regression tests and verification steps are provided above.
• 🤓 No new dependencies are introduced.
• 😮 The changes do not introduce malicious code.

[sourcery-ai]

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