Phase 3: AI integration with Ollama via Python sidecar

- sidecar: FastAPI app with /embed, /generate, /rerank hitting Ollama
- sidecar: Dockerfile, env var config (EMBED_MODEL, GEN_MODEL, RERANK_MODEL)
- aibridge: reqwest HTTP client with typed request/response structs
- aibridge: Axum proxy endpoints (POST /ai/embed, /ai/generate, /ai/rerank)
- gateway: wires AiClient with SIDECAR_URL env var
- e2e verified: nomic-embed-text returns 768d vectors, qwen2.5 generates text

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

crates/aibridge/src/service.rs

@@ -1,9 +1,60 @@
-use axum::{Router, routing::get};
+use axum::{
+    Json, Router,
+    extract::State,
+    http::StatusCode,
+    response::IntoResponse,
+    routing::{get, post},
+};
 
-pub fn router() -> Router {
-    Router::new().route("/health", get(health))
+use crate::client::{
+    AiClient, EmbedRequest, GenerateRequest, RerankRequest,
+};
+
+pub fn router(client: AiClient) -> Router {
+    Router::new()
+        .route("/health", get(health))
+        .route("/embed", post(embed))
+        .route("/generate", post(generate))
+        .route("/rerank", post(rerank))
+        .with_state(client)
 }
 
-async fn health() -> &'static str {
-    "aibridge ok"
+async fn health(State(client): State<AiClient>) -> impl IntoResponse {
+    match client.health().await {
+        Ok(info) => Ok(Json(info)),
+        Err(e) => Err((StatusCode::BAD_GATEWAY, format!("sidecar down: {e}"))),
+    }
+}
+
+async fn embed(
+    State(client): State<AiClient>,
+    Json(req): Json<EmbedRequest>,
+) -> impl IntoResponse {
+    tracing::info!("embedding {} texts", req.texts.len());
+    match client.embed(req).await {
+        Ok(resp) => Ok(Json(resp)),
+        Err(e) => Err((StatusCode::BAD_GATEWAY, e)),
+    }
+}
+
+async fn generate(
+    State(client): State<AiClient>,
+    Json(req): Json<GenerateRequest>,
+) -> impl IntoResponse {
+    tracing::info!("generating with prompt len={}", req.prompt.len());
+    match client.generate(req).await {
+        Ok(resp) => Ok(Json(resp)),
+        Err(e) => Err((StatusCode::BAD_GATEWAY, e)),
+    }
+}
+
+async fn rerank(
+    State(client): State<AiClient>,
+    Json(req): Json<RerankRequest>,
+) -> impl IntoResponse {
+    tracing::info!("reranking {} documents", req.documents.len());
+    match client.rerank(req).await {
+        Ok(resp) => Ok(Json(resp)),
+        Err(e) => Err((StatusCode::BAD_GATEWAY, e)),
+    }
 }