fix(feishu): support reading WebSocket rendered card content

[JiajunBernoulli]

Problem

Feishu cards arriving via WebSocket have a different structure than expected. The function returned empty results, causing cards to be displayed as placeholder.

Root Cause

Three structural mismatches between actual WebSocket card format and code expectations:

1. Nested list elements: is (list of lists), not (flat list)
2. Text element format: Rendered cards use with field, not with field
3. Missing user_dsl: Original card definition is in JSON string field, not used by extraction code

Fix

Three minimal changes to :

1. Extract first (richest source for original card data)
2. Handle nested list format (detect is list)
3. Add handler in
4. Support (schema 2.0 format)

Testing

Verified with actual Feishu card messages - bot now correctly reads card content including markdown, tables, and structured data.

[JiajunBernoulli]

【需求背景】我会将一些Bot发送的消息卡片直接转发给Nanobot处理，但是当前的Nanobot无法读取飞书卡片
【测试用例】
修复前飞书读不到nanobot发出的卡片

修复后可以读到nanobot发出的卡片

[chengyongru]

Pushed a maintainer fix for the Feishu card parser: table components now extract column headers and row values instead of falling back to [interactive], and the parser has regression coverage for user_dsl, nested rendered text elements, and table rows.

[chengyongru]

@JiajunBernoulli 我做了一点改动，可以看看是不是符合你的预期💖

[JiajunBernoulli]

@JiajunBernoulli 我做了一点改动，可以看看是不是符合你的预期💖

LGTM

[Re-bin]

LGTM. This fixes a real Feishu card ingestion gap: WebSocket-rendered interactive cards now extract useful content from user_dsl, nested rendered text elements, schema 2.0 body elements, and table rows instead of falling back to [interactive].

I also checked the maintainer follow-up around table extraction, and the author confirmed the behavior matches expectations.

Validated locally:

• python -m pytest tests/channels/test_feishu_card_extraction.py tests/channels/test_feishu_login.py tests/channels/test_feishu_streaming.py -q
• python -m ruff check nanobot/channels/feishu.py tests/channels/test_feishu_card_extraction.py