refactor: 大规模模块拆分与代码精简，新增 ai-pipeline/data-contracts 独立 crate

- 新增 aether-ai-pipeline 和 aether-data-contracts crate，将 pipeline 逻辑与数据契约从 gateway 中解耦
- 重构 admin handlers：拆分单体模块为 auth/billing/endpoint/features/model/observability/provider/system 等独立子模块
- 合并 chat/cli 重复代码路径：精简 conversion、finalize、planner 中的 sync/chat/cli 分支
- 重构 scheduler/executor/data 层，引入 facade 模式降低模块间耦合
- 移除冗余的 intent 模块，将 plan_fallback/policy/stream_path/sync_path 迁移至 executor
- 前端适配：调整 admin API 调用和 provider 模型测试对话框

crates/aether-ai-pipeline/src/adaptation/mod.rs

@@ -0,0 +1 @@
+pub mod surfaces;

crates/aether-ai-pipeline/src/adaptation/surfaces.rs

@@ -0,0 +1,188 @@
+pub const ANTIGRAVITY_PROVIDER_TYPE: &str = "antigravity";
+pub const KIRO_PROVIDER_TYPE: &str = "kiro";
+pub const KIRO_ENVELOPE_NAME: &str = "kiro:generateAssistantResponse";
+pub const ANTIGRAVITY_V1INTERNAL_ENVELOPE_NAME: &str = "antigravity:v1internal";
+pub const GEMINI_CLI_V1INTERNAL_ENVELOPE_NAME: &str = "gemini_cli:v1internal";
+
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+pub enum ProviderAdaptationSurface {
+    AntigravityGeminiChat,
+    AntigravityGeminiCli,
+    GeminiCliV1Internal,
+    KiroClaudeCli,
+}
+
+#[derive(Debug, Clone, Copy)]
+pub struct ProviderAdaptationDescriptor {
+    pub surface: ProviderAdaptationSurface,
+    pub provider_type: Option<&'static str>,
+    pub envelope_name: &'static str,
+    pub anchor_api_format: &'static str,
+    pub supports_request_bridge: bool,
+    pub supports_sync_finalize_bridge: bool,
+    pub supports_stream_bridge: bool,
+    pub requires_eventstream_accept: bool,
+    pub unwraps_response_envelope: bool,
+}
+
+const PROVIDER_ADAPTATION_SURFACES: &[ProviderAdaptationDescriptor] = &[
+    ProviderAdaptationDescriptor {
+        surface: ProviderAdaptationSurface::AntigravityGeminiChat,
+        provider_type: Some(ANTIGRAVITY_PROVIDER_TYPE),
+        envelope_name: ANTIGRAVITY_V1INTERNAL_ENVELOPE_NAME,
+        anchor_api_format: "gemini:chat",
+        supports_request_bridge: true,
+        supports_sync_finalize_bridge: true,
+        supports_stream_bridge: true,
+        requires_eventstream_accept: false,
+        unwraps_response_envelope: true,
+    },
+    ProviderAdaptationDescriptor {
+        surface: ProviderAdaptationSurface::AntigravityGeminiCli,
+        provider_type: Some(ANTIGRAVITY_PROVIDER_TYPE),
+        envelope_name: ANTIGRAVITY_V1INTERNAL_ENVELOPE_NAME,
+        anchor_api_format: "gemini:cli",
+        supports_request_bridge: true,
+        supports_sync_finalize_bridge: true,
+        supports_stream_bridge: true,
+        requires_eventstream_accept: false,
+        unwraps_response_envelope: true,
+    },
+    ProviderAdaptationDescriptor {
+        surface: ProviderAdaptationSurface::GeminiCliV1Internal,
+        provider_type: None,
+        envelope_name: GEMINI_CLI_V1INTERNAL_ENVELOPE_NAME,
+        anchor_api_format: "gemini:cli",
+        supports_request_bridge: false,
+        supports_sync_finalize_bridge: true,
+        supports_stream_bridge: true,
+        requires_eventstream_accept: false,
+        unwraps_response_envelope: true,
+    },
+    ProviderAdaptationDescriptor {
+        surface: ProviderAdaptationSurface::KiroClaudeCli,
+        provider_type: Some(KIRO_PROVIDER_TYPE),
+        envelope_name: KIRO_ENVELOPE_NAME,
+        anchor_api_format: "claude:cli",
+        supports_request_bridge: true,
+        supports_sync_finalize_bridge: true,
+        supports_stream_bridge: true,
+        requires_eventstream_accept: true,
+        unwraps_response_envelope: false,
+    },
+];
+
+pub fn provider_adaptation_descriptor_for_envelope(
+    envelope_name: &str,
+    provider_api_format: &str,
+) -> Option<&'static ProviderAdaptationDescriptor> {
+    let envelope_name = envelope_name.trim();
+    let provider_api_format = provider_api_format.trim().to_ascii_lowercase();
+    PROVIDER_ADAPTATION_SURFACES.iter().find(|descriptor| {
+        descriptor.envelope_name.eq_ignore_ascii_case(envelope_name)
+            && descriptor
+                .anchor_api_format
+                .eq_ignore_ascii_case(provider_api_format.as_str())
+    })
+}
+
+pub fn provider_adaptation_descriptor_for_provider_type(
+    provider_type: &str,
+    provider_api_format: &str,
+) -> Option<&'static ProviderAdaptationDescriptor> {
+    let provider_type = provider_type.trim();
+    let provider_api_format = provider_api_format.trim().to_ascii_lowercase();
+    PROVIDER_ADAPTATION_SURFACES.iter().find(|descriptor| {
+        descriptor
+            .provider_type
+            .is_some_and(|value| value.eq_ignore_ascii_case(provider_type))
+            && descriptor
+                .anchor_api_format
+                .eq_ignore_ascii_case(provider_api_format.as_str())
+    })
+}
+
+pub fn provider_adaptation_anchor_api_format(
+    envelope_name: &str,
+    provider_api_format: &str,
+) -> Option<&'static str> {
+    provider_adaptation_descriptor_for_envelope(envelope_name, provider_api_format)
+        .map(|descriptor| descriptor.anchor_api_format)
+}
+
+pub fn provider_adaptation_allows_sync_finalize_envelope(
+    envelope_name: &str,
+    provider_api_format: &str,
+) -> bool {
+    provider_adaptation_descriptor_for_envelope(envelope_name, provider_api_format)
+        .is_some_and(|descriptor| descriptor.supports_sync_finalize_bridge)
+}
+
+pub fn provider_adaptation_requires_eventstream_accept(
+    envelope_name: Option<&str>,
+    provider_api_format: &str,
+) -> bool {
+    envelope_name
+        .and_then(|value| provider_adaptation_descriptor_for_envelope(value, provider_api_format))
+        .is_some_and(|descriptor| descriptor.requires_eventstream_accept)
+}
+
+pub fn provider_adaptation_should_unwrap_stream_envelope(
+    envelope_name: &str,
+    provider_api_format: &str,
+) -> bool {
+    provider_adaptation_descriptor_for_envelope(envelope_name, provider_api_format)
+        .is_some_and(|descriptor| descriptor.unwraps_response_envelope)
+}
+
+#[cfg(test)]
+mod tests {
+    use super::{
+        provider_adaptation_allows_sync_finalize_envelope, provider_adaptation_anchor_api_format,
+        provider_adaptation_requires_eventstream_accept,
+        provider_adaptation_should_unwrap_stream_envelope, ANTIGRAVITY_V1INTERNAL_ENVELOPE_NAME,
+        GEMINI_CLI_V1INTERNAL_ENVELOPE_NAME, KIRO_ENVELOPE_NAME,
+    };
+
+    #[test]
+    fn resolves_private_surface_anchor_contracts() {
+        assert_eq!(
+            provider_adaptation_anchor_api_format(
+                ANTIGRAVITY_V1INTERNAL_ENVELOPE_NAME,
+                "gemini:cli"
+            ),
+            Some("gemini:cli")
+        );
+        assert_eq!(
+            provider_adaptation_anchor_api_format(
+                GEMINI_CLI_V1INTERNAL_ENVELOPE_NAME,
+                "gemini:cli"
+            ),
+            Some("gemini:cli")
+        );
+        assert_eq!(
+            provider_adaptation_anchor_api_format(KIRO_ENVELOPE_NAME, "claude:cli"),
+            Some("claude:cli")
+        );
+    }
+
+    #[test]
+    fn exposes_private_surface_capabilities() {
+        assert!(provider_adaptation_allows_sync_finalize_envelope(
+            ANTIGRAVITY_V1INTERNAL_ENVELOPE_NAME,
+            "gemini:chat"
+        ));
+        assert!(provider_adaptation_should_unwrap_stream_envelope(
+            GEMINI_CLI_V1INTERNAL_ENVELOPE_NAME,
+            "gemini:cli"
+        ));
+        assert!(provider_adaptation_requires_eventstream_accept(
+            Some(KIRO_ENVELOPE_NAME),
+            "claude:cli"
+        ));
+        assert!(!provider_adaptation_requires_eventstream_accept(
+            Some(ANTIGRAVITY_V1INTERNAL_ENVELOPE_NAME),
+            "gemini:cli"
+        ));
+    }
+}