Add Feishu advanced policy UI and manager support for DM/Group permissions

[Yidada]

Motivation

• Provide a user-facing "高级设置" panel to inspect and edit Feishu Channel DM and Group permission policies without using the CLI.
• Enable reading and writing the underlying openclaw configuration keys (channels.feishu.*) to support "仅自己 / 指定 UID / 全开放" modes.
• Keep existing onboarding, install and binding flows unchanged while exposing a safe, folded advanced editor.

Description

• Added FeishuPermissionMode, FeishuAdvancedPolicySnapshot, and FeishuAdvancedPolicyDraft models to represent UI modes and drafts.
• Implemented loadAdvancedPolicy() and saveAdvancedPolicy(_:) on OpenClawFeishuChannelManager to read/write configs via the openclaw CLI and update advancedPolicySnapshot, advancedPolicyBusy, and advancedPolicyError.
• Added normalization and resolution helpers (normalizeAdvancedPolicyDraft, normalizeUIDs, resolveAdvancedPolicySnapshot, and mergeUniqueString usage) and included advancedPolicyBusy in isBusy.
• Extended ChannelsManagementView with state bindings, an expandable DisclosureGroup UI (feishuAdvancedPolicyPanel) for Owner Open ID, DM and Group policy pickers, UID inputs, and actions to read/save; added onChange/onReceive hooks to sync manager snapshot to the UI.
• Added splitUIDText helper, updated UI layout to place the panel below the binding button and above logs, and appended a design doc docs/2026-04-08-feishu-advanced-policy-settings-design.md.
• Added unit tests in OpenClawFeishuChannelManagerTests covering loadAdvancedPolicy resolution and saveAdvancedPolicy write behavior.

Testing

• Ran the updated unit tests in Tests/ClawbarTests/OpenClawFeishuChannelManagerTests, including testLoadAdvancedPolicyResolvesSelectedAndOnlyMeModes and testSaveAdvancedPolicyWritesOnlyMeAndOpenConfigs, and they passed.
• Verified existing manager command mocks and recording-based tests continue to exercise the openclaw config get/set sequences using the RecordingCommandRunner mocks.
• No UI snapshot tests were added; manual UI integration is guarded by the panel being collapsed by default.

---

Codex Task