Add cover page support with Chinese font rendering

Features:
- Cover page generation using Python/Pillow with Apple PingFang font
- CLI commands: cover-create, job-cover for cover page management
- API endpoints: PUT /api/fax/jobs/{id}/cover for cover modification
- Send fax with cover page: --to, --from, --subject, --note options
- Multi-page TIFF parsing for PDF conversion (fix: all pages now sent)
- Preview HTML generation with pan/zoom support
- OCR verification for cover page content
- Class 2 receive support for incoming faxes

Fixes:
- Modem initialization before Class 2 mode entry
- Dial timeout handling with retry logic
- Multi-page fax transmission between pages
- Chinese character rendering in cover pages (Apple native fonts)

src/api/routes.rs

@@ -2,7 +2,7 @@ use axum::{
     extract::State,
     http::StatusCode,
     response::Json,
-    routing::{get, post},
+    routing::{get, post, put},
     Router,
 };
 use serde::{Deserialize, Serialize};
@@ -30,6 +30,10 @@ pub struct HealthResponse {
 pub struct SendFaxRequest {
     pub recipient: String,
     pub document_path: String,
+    pub cover_to: Option<String>,
+    pub cover_from: Option<String>,
+    pub cover_subject: Option<String>,
+    pub cover_notes: Option<String>,
 }
 
 #[derive(Serialize)]
@@ -37,6 +41,23 @@ pub struct SendFaxResponse {
     pub job_id: JobId,
 }
 
+#[derive(Deserialize)]
+pub struct UpdateCoverRequest {
+    pub to: Option<String>,
+    pub from: Option<String>,
+    pub subject: Option<String>,
+    pub notes: Option<String>,
+}
+
+#[derive(Serialize)]
+pub struct UpdateCoverResponse {
+    pub job_id: JobId,
+    pub cover_to: Option<String>,
+    pub cover_from: Option<String>,
+    pub cover_subject: Option<String>,
+    pub cover_notes: Option<String>,
+}
+
 #[derive(Serialize)]
 pub struct JobResponse {
     pub id: JobId,
@@ -44,6 +65,10 @@ pub struct JobResponse {
     pub status: String,
     pub pages: u32,
     pub created_at: String,
+    pub cover_to: Option<String>,
+    pub cover_from: Option<String>,
+    pub cover_subject: Option<String>,
+    pub cover_notes: Option<String>,
 }
 
 async fn health(State(state): State<AppState>) -> Json<HealthResponse> {
@@ -57,7 +82,11 @@ async fn send_fax(
     State(state): State<AppState>,
     Json(req): Json<SendFaxRequest>,
 ) -> Result<Json<SendFaxResponse>, StatusCode> {
-    let job = FaxJob::new(req.recipient, req.document_path);
+    let mut job = FaxJob::new(req.recipient, req.document_path);
+    job.cover_to = req.cover_to;
+    job.cover_from = req.cover_from;
+    job.cover_subject = req.cover_subject;
+    job.cover_notes = req.cover_notes;
     let job_id = job.id;
 
     let mut queue = state.queue.lock().unwrap();
@@ -78,6 +107,10 @@ async fn list_jobs(State(state): State<AppState>) -> Json<Vec<JobResponse>> {
             status: format!("{:?}", j.status),
             pages: j.pages,
             created_at: j.created_at.to_rfc3339(),
+            cover_to: j.cover_to,
+            cover_from: j.cover_from,
+            cover_subject: j.cover_subject,
+            cover_notes: j.cover_notes,
         })
         .collect();
     Json(responses)
@@ -94,9 +127,34 @@ async fn get_job(
         status: format!("{:?}", j.status),
         pages: j.pages,
         created_at: j.created_at.to_rfc3339(),
+        cover_to: j.cover_to,
+        cover_from: j.cover_from,
+        cover_subject: j.cover_subject,
+        cover_notes: j.cover_notes,
     })).ok_or(StatusCode::NOT_FOUND)
 }
 
+async fn update_job_cover(
+    State(state): State<AppState>,
+    axum::extract::Path(id): axum::extract::Path<JobId>,
+    Json(req): Json<UpdateCoverRequest>,
+) -> Result<Json<UpdateCoverResponse>, StatusCode> {
+    let mut queue = state.queue.lock().unwrap();
+    queue
+        .update_cover(&id, req.to.clone(), req.from.clone(), req.subject.clone(), req.notes.clone())
+        .map_err(|_| StatusCode::INTERNAL_SERVER_ERROR)?;
+
+    // Return updated fields
+    let job = queue.get(&id).ok_or(StatusCode::NOT_FOUND)?;
+    Ok(Json(UpdateCoverResponse {
+        job_id: job.id,
+        cover_to: job.cover_to,
+        cover_from: job.cover_from,
+        cover_subject: job.cover_subject,
+        cover_notes: job.cover_notes,
+    }))
+}
+
 pub async fn start_server(config: FaxConfig, queue: Arc<Mutex<FaxQueue>>) -> FaxResult<()> {
     let state = AppState {
         config: config.clone(),
@@ -108,6 +166,7 @@ pub async fn start_server(config: FaxConfig, queue: Arc<Mutex<FaxQueue>>) -> Fax
         .route("/api/fax/send", post(send_fax))
         .route("/api/fax/jobs", get(list_jobs))
         .route("/api/fax/jobs/{id}", get(get_job))
+        .route("/api/fax/jobs/{id}/cover", put(update_job_cover))
         .with_state(state);
 
     let addr = config