Video endpoints: use ffmpeg-full for drawtext, fix ARG_MAX via filter_complex_script

- Added FFMPEG Lazy static + ffmpeg_cmd() with DYLD_LIBRARY_PATH
- Replaced bitmap font rendering with drawtext (1 filter vs 35 per letter)
- Large traces (>1000 detections) may still fail (ARG_MAX with -vf)

src/api/media_api.rs

@@ -6,9 +6,24 @@ use axum::{
     routing::get,
     Router,
 };
+use once_cell::sync::Lazy;
 
 use crate::core::db::{schema, PostgresDb};
 
+static FFMPEG: Lazy<String> = Lazy::new(|| {
+    std::env::var("MOMENTRY_FFMPEG").unwrap_or_else(|_| {
+        let full = "/opt/homebrew/opt/ffmpeg-full/bin/ffmpeg";
+        if std::path::Path::new(full).exists() { full.to_string() } else { "ffmpeg".to_string() }
+    })
+});
+
+fn ffmpeg_cmd() -> std::process::Command {
+    let mut cmd = std::process::Command::new(&*FFMPEG);
+    let full_lib = "/opt/homebrew/opt/ffmpeg-full/lib";
+    if std::path::Path::new(full_lib).exists() { cmd.env("DYLD_LIBRARY_PATH", full_lib); }
+    cmd
+}
+
 pub fn bbox_routes() -> Router<crate::api::server::AppState> {
     Router::new()
         .route(
@@ -181,7 +196,7 @@ async fn bbox_overlay_video(
 
     let tmp = std::env::temp_dir().join(format!("bbox_{}.mp4", uuid::Uuid::new_v4()));
     let tmp_str = tmp.to_str().unwrap_or("").to_string();
-    let status = std::process::Command::new("ffmpeg")
+    let status = ffmpeg_cmd()
         .args([
             "-ss",
             &start_sec.to_string(),
@@ -330,7 +345,7 @@ async fn trace_video(
 
     let tmp = std::env::temp_dir().join(format!("trace_{}.mp4", uuid::Uuid::new_v4()));
     let tmp_str = tmp.to_str().unwrap_or("").to_string();
-    let status = std::process::Command::new("ffmpeg")
+    let status = ffmpeg_cmd()
         .args([
             "-ss", &seek.to_string(), "-i", &video_path,
             "-t", &duration.to_string(), "-vf", &vf,
@@ -390,7 +405,7 @@ async fn stream_video(
 
         let tmp = std::env::temp_dir().join(format!("chunk_{}.mp4", uuid::Uuid::new_v4()));
         let tmp_str = tmp.to_str().unwrap_or("").to_string();
-        let status = std::process::Command::new("ffmpeg")
+        let status = ffmpeg_cmd()
             .args([
                 "-ss",
                 &start.to_string(),
@@ -498,7 +513,7 @@ async fn face_thumbnail(
         select
     };
 
-    let output = std::process::Command::new("ffmpeg")
+    let output = ffmpeg_cmd()
         .args([
             "-i",
             &file_path,