What does this PR do?

Serializes card.data to a JSON string in both _handle_approval_card_action and _handle_update_prompt_card_action callbacks. The Feishu API requires card.data to be a JSON string, but both handlers were passing raw Python dicts, causing error 200340 when users click approval or update-prompt buttons on interactive cards.

Related Issue

Fixes #38305, Fixes #10251, Fixes #10073, Fixes #8246, Fixes #13924

Type of Change

• 🐛 Bug fix (non-breaking change that fixes an issue)

Changes Made

• gateway/platforms/feishu.py: Wrap card.data assignments in _handle_approval_card_action (line 2639) and _handle_update_prompt_card_action (line 2696) with json.dumps(ensure_ascii=False) so the Feishu API receives a JSON string instead of a Python dict.
• tests/gateway/test_feishu_approval_buttons.py: Update 6 test assertions to verify card.data is a str (via isinstance check) and parse it with json.loads() before accessing dict keys.

How to Test

1. pytest tests/gateway/test_feishu_approval_buttons.py -v — all 38 tests pass
2. On a live Feishu bot: trigger an exec approval → click "Approve" or "Deny" → card should update without error 200340
3. Trigger a /update prompt → click "Yes" or "No" → card should update without error 200340

Checklist

Code

• I've read the Contributing Guide
• My commit messages follow Conventional Commits (fix(scope):, feat(scope):, etc.)
• I searched for existing PRs to make sure this isn't a duplicate
• My PR contains only changes related to this fix/feature (no unrelated commits)
• I've run pytest tests/gateway/test_feishu_approval_buttons.py -v and all 38 tests pass
• I've added tests for my changes (required for bug fixes, strongly encouraged for features)
• I've tested on my platform: macOS

Documentation & Housekeeping

• I've updated relevant documentation (README, docs/, docstrings) — or N/A
• I've updated cli-config.yaml.example if I added/changed config keys — or N/A
• I've updated CONTRIBUTING.md or AGENTS.md if I changed architecture or workflows — or N/A
• I've considered cross-platform impact (Windows, macOS) per the compatibility guide — or N/A (Feishu platform adapter, no OS-specific behavior)
• I've updated tool descriptions/schemas if I changed tool behavior — or N/A

Code Intelligence

• Analyzed: gateway/platforms/feishu.py → _handle_approval_card_action, _handle_update_prompt_card_action, _build_resolved_approval_card, _build_resolved_update_prompt_card
• Callers of _build_resolved_approval_card: 1 (line 2639)
• Callers of _build_resolved_update_prompt_card: 1 (line 2696)
• Blast radius: LOW — only affects Feishu card callback responses, no other callers
• Related patterns: PR fix(feishu): serialize approval callback card data to JSON string #10256 attempted the same fix but targeted stale line numbers (line 1909 vs current 2639). This PR applies the fix to the current codebase and also covers the _handle_update_prompt_card_action handler that fix(feishu): serialize approval callback card data to JSON string #10256 missed.