feat(dl): replace Transmission with qBittorrent

qBittorrent's add call answers `Ok.` and nothing else — no hash, no name,
no duplicate signal — so arr derives the v1 infohash from the magnet or the
`.torrent` bytes before the call and looks the torrent up by it. That also
drops Transmission's numeric torrent id: the hash is the only identity now.

The reaper needs "stopped because a share limit was reached", and
qBittorrent's state field cannot tell that apart from a hand-paused torrent.
So the ratio and idle counters are checked against the limits arr set, and a
torrent stopped by a global limit reads as still seeding rather than being
deleted.

The WebUI needs a login, so `ARR_QBITTORRENT_USERNAME` and
`ARR_QBITTORRENT_PASSWORD` join the env-only secrets; leaving both unset is
valid for an instance that whitelists arr's subnet.

Verified against qBittorrent 5 (WebAPI 2.15.1) in a container: it rejects
`setShareLimits` without `shareLimitAction`, which 4.x ignores, so it is
always sent.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

web/src/downloads.ts

@@ -17,7 +17,7 @@ export interface Download {
 }
 
 /** §9.8: the live snapshot, degrading to nothing rather than breaking the
- * page it decorates — Transmission or the daemon being down is a fact the
+ * page it decorates — qBittorrent or the daemon being down is a fact the
  * signal chain already reports, not something this poll repeats. */
 export async function fetchDownloads(): Promise<Download[]> {
   try {

web/src/health.ts

@@ -28,7 +28,7 @@ export interface HealthReport {
   status: "ok" | "degraded";
   version: string;
   prowlarr: Check;
-  transmission: Check;
+  qbit: Check;
   tmdb: Check;
   subtitles: SubtitleHealth;
 }

web/src/main.ts

@@ -271,7 +271,7 @@ function main() {
   const checks = {
     tmdb: moduleRefs("tmdb"),
     prowlarr: moduleRefs("prowlarr"),
-    transmission: moduleRefs("transmission"),
+    qbit: moduleRefs("qbit"),
   } as const;
 
   const traces = {
@@ -293,7 +293,7 @@ function main() {
   }
 
   // stagger order for the one power-up animation, upstream to downstream
-  const strikeOrder = [checks.tmdb, checks.prowlarr, master, checks.transmission];
+  const strikeOrder = [checks.tmdb, checks.prowlarr, master, checks.qbit];
   strikeOrder.forEach((refs, index) => {
     refs.lamp.style.setProperty("--strike", String(index));
   });
@@ -331,7 +331,7 @@ function main() {
 
     setModule(master, degraded ? "degraded" : "ok", degraded ? "warn" : "ok", report.status);
     setTrace("master", degraded ? "warn" : "ok");
-    for (const name of ["tmdb", "prowlarr", "transmission"] as const) {
+    for (const name of ["tmdb", "prowlarr", "qbit"] as const) {
       const check = report[name];
       setModule(
         checks[name],
@@ -340,7 +340,7 @@ function main() {
         check.status,
         check.detail,
       );
-      if (name !== "transmission") {
+      if (name !== "qbit") {
         setTrace(name, TONE_BY_STATUS[check.status]);
       }
     }

web/src/releases.ts

@@ -129,7 +129,7 @@ export interface SeasonPackState {
  * the release is blacklisted and every episode it covered reopens as a gap.
  * Nothing on screen joined those facts, so the season read `0/10` as though
  * no grab had ever been tried and the operator found out by opening
- * Transmission.
+ * qBittorrent.
  */
 export interface ImportFailure {
   release: string;

web/src/style.css

@@ -308,7 +308,7 @@ body {
   grid-area: out;
 }
 
-.area-transmission {
+.area-qbittorrent {
   grid-area: sink;
 }