Upgrade Transmission to 4.1.1 (#282)

## Summary
- Upgrade Transmission from 4.0.6-r4 to 4.1.1-r1
- Uses Alpine edge community repo for transmission packages, keeping stable alpine:3.22 base
- Fix stale image reference in service doc (was linuxserver, now custom registry image)
- Mark transmission as reviewed in service-versions.yaml

## Context
Service review found Transmission two minor versions behind (4.0.6 → 4.1.1). Alpine 3.22 only packages 4.0.6, so transmission is installed from edge's community repo with an exact version pin.

4.1.0 added improved µTP performance, IPv6/dual-stack UDP tracker, JSON-RPC 2.0 API. 4.1.1 is a bugfix release (20+ fixes).

Dagger test build passed locally.

## Deployment and Testing
- [ ] Build container via Forgejo workflow (`mise run container-build-and-release transmission`)
- [ ] Update kustomization.yaml with new image tag
- [ ] `argocd app set torrent --revision feature/transmission-review && argocd app sync torrent`
- [ ] Verify web UI at https://torrent.ops.eblu.me
- [ ] Check Grafana Transmission dashboard still receives metrics
- [ ] After merge: `argocd app set torrent --revision main && argocd app sync torrent`

## Note
The transmission-exporter sidecar (OOMKilling every ~30min, 294 restarts) is being tracked separately as a future replacement project.

Reviewed-on: #282

containers/transmission/Dockerfile

@@ -1,17 +1,20 @@
 # Transmission BitTorrent daemon
 # Simpler alternative to linuxserver image
 
-ARG CONTAINER_APP_VERSION=4.0.6-r4
+ARG CONTAINER_APP_VERSION=4.1.1-r1
 
 FROM alpine:3.22
 
 ARG CONTAINER_APP_VERSION
 ARG TRANSMISSION_VERSION=${CONTAINER_APP_VERSION}
 
+# Transmission 4.1.x is only in edge; base OS stays on stable 3.22
 RUN apk add --no-cache \
+    --repository=https://dl-cdn.alpinelinux.org/alpine/edge/community \
     transmission-daemon=${TRANSMISSION_VERSION} \
     transmission-cli=${TRANSMISSION_VERSION} \
     transmission-remote=${TRANSMISSION_VERSION} \
+    && apk add --no-cache \
     bash \
     curl \
     tzdata \