feat(web): wire session-telemetry-otel into the dsh web composition

Mount the existing telemetry seam + OTel logs backend in the web/headless
config tree so every session-log event streams to an OTLP/HTTP collector:

- telemetry-otel row: url defaults to the standard local OTLP endpoint,
  DSH_TELEMETRY_OTLP_URL overrides; 10s batch cadence; exporter/processor
  values bound the shutdown drain to ~1s against an unreachable collector
  (timeoutMillis doubles as the retry deadline, single-batch drain).
- DSH_TELEMETRY_DISABLED opt-out: AppCLIEntry patches the row disabled
  before boot (config alone cannot disable a row, and exporter.url
  validation is load-time fail-loud).

apps/cli/package.json

@@ -81,6 +81,7 @@
     "@deepseek-ai/dsh-session-projection-cache": "workspace:^",
     "@deepseek-ai/dsh-session-query-sqlite": "workspace:^",
     "@deepseek-ai/dsh-session-reference": "workspace:^",
+    "@deepseek-ai/dsh-session-telemetry-otel": "workspace:^",
     "@deepseek-ai/dsh-session-title": "workspace:^",
     "@deepseek-ai/dsh-session-title-first-message-llm": "workspace:^",
     "@deepseek-ai/dsh-settings-local": "workspace:^",