chore(infra): migrate Jaeger to v2 for built-in dark theme

Jaeger v1's web UI has no theme selector — it ships light-only.
v2 (the OTel-Collector-based rewrite, image
`jaegertracing/jaeger`, distinct from v1's `jaegertracing/
all-in-one`) ships a Light / Dark / Auto switcher in the UI nav.
v2 is also the actively-developed line; v1 will be phased out
within ~6-12 months.

Migration is mechanical:

- Image: `jaegertracing/all-in-one:1.76.0` →
  `jaegertracing/jaeger:2.17.0`.
- Drop `COLLECTOR_OTLP_ENABLED: 'true'` env — v2 enables OTLP
  receivers by default.
- UI port (16686) and OTLP ports (4317 / 4318) are unchanged, so
  the collector → jaeger:4317 forwarding pipeline keeps working
  without touching `otel-collector.yaml`.

The compose comment is updated to reflect v2's distinct image
name and UI capabilities.

infra/local/dev.compose.yml

@@ -133,14 +133,19 @@ services:
   # OTLP ports (4317/4318) are NOT published from this service to
   # avoid colliding with the collector — the collector talks to
   # Jaeger on the internal Compose network.
+  #
+  # Image is Jaeger v2 (`jaegertracing/jaeger`, distinct from the v1
+  # `jaegertracing/all-in-one`). v2 is the rewrite built on top of
+  # OpenTelemetry Collector and is the actively-developed line. OTLP
+  # receivers are enabled by default (no COLLECTOR_OTLP_ENABLED env
+  # needed) and the UI ships a built-in Light/Dark/Auto theme
+  # selector — features the v1 image did not have.
   # ------------------------------------------------------------------
   jaeger:
-    image: jaegertracing/all-in-one:1.76.0
+    image: jaegertracing/jaeger:2.17.0
     container_name: apf-portal-jaeger
     restart: unless-stopped
     profiles: [observability]
-    environment:
-      COLLECTOR_OTLP_ENABLED: 'true'
     ports:
       - '${JAEGER_UI_PORT:-16686}:16686'
     networks: