fix: ffmpeg version detection and player letterboxing

ffmpeg only accepts -version (single dash); it exits 8 on --version and
writes to stderr, so the status panel reported it missing even when
installed. Version flags are now per-tool and both streams are read.

The player used max-h-full inside a grid, which a 1080x1920 Short
overflowed. Switched to absolute fill with object-contain so portrait
and landscape both letterbox correctly.

Also sized the window to 1180x780 centered, which fits a laptop display.

src-tauri/tests/seed_real_db.rs

@@ -0,0 +1,56 @@
+//! Populates the installed app's database using the app's own code paths, so
+//! the UI can be verified against real data without driving the file dialog.
+//! Run with: cargo test --test seed_real_db -- --ignored --nocapture
+
+use flighttube_lib::{db::Db, feed, models::FeedFilter, thumbs};
+use std::path::PathBuf;
+
+fn app_data() -> PathBuf {
+    PathBuf::from(std::env::var("HOME").unwrap())
+        .join("Library/Application Support/com.vincent.flighttube")
+}
+
+#[tokio::test]
+#[ignore]
+async fn seed() {
+    let dir = app_data();
+    let mut db = Db::open(&dir.join("flighttube.db")).expect("open real db");
+
+    let channels = db.channel_ids().unwrap();
+    println!("channels in db: {}", channels.len());
+    assert!(!channels.is_empty(), "seed channels first");
+
+    let http = reqwest::Client::builder()
+        .user_agent("FlightTube/0.1 (+desktop)")
+        .timeout(std::time::Duration::from_secs(20))
+        .build()
+        .unwrap();
+
+    let mut total = 0;
+    for cid in &channels {
+        if let Ok(v) = feed::fetch_channel(&http, cid).await {
+            total += v.len();
+            db.upsert_videos(&v).unwrap();
+        }
+    }
+    println!("videos upserted: {total}");
+
+    // Cache thumbnails so the feed renders with no network.
+    let pending = db.videos_missing_thumbs(400).unwrap();
+    println!("thumbnails to cache: {}", pending.len());
+    let tdir = thumbs::cache_dir(&dir);
+    let mut ok = 0;
+    for (id, url) in pending {
+        if let Ok(p) = thumbs::cache_one(&http, &id, &url, &tdir).await {
+            db.set_thumb_path(&id, &p.to_string_lossy()).unwrap();
+            ok += 1;
+        }
+    }
+    println!("thumbnails cached: {ok}");
+
+    let feed_rows = db.list_feed(&FeedFilter::default()).unwrap();
+    println!("feed rows now: {}", feed_rows.len());
+    for i in feed_rows.iter().take(3) {
+        println!("  [{}] {}", i.channel_title, i.title);
+    }
+}