fix(profiling): use Dynamo control/ engine routes for start/stop_profile

[shyeh25]

Dynamo moved its control-plane engine routes under a control/ namespace in ai-dynamo/dynamo#10347 (e6fd808c0f, 2026-06-15):

• register_engine_route("start_profile", ...)

• register_engine_route("control/start_profile", ...)

So any Dynamo build ≥ #10347 serves the profiler-trigger at /engine/control/start_profile (and /engine/control/stop_profile), not the old /engine/start_profile.

srt-slurm's profiling client (lib/profiling.sh) was still POSTing the old paths. Against a current Dynamo this silently 404s → the profiler is never armed → prefill/decode nsys
(and torch) profiles come out empty. There's no error surfaced because the call is best-effort (curl -f ... || Warning).

This patch points the dynamo frontend branch at the new control/ routes.

Scope / safety:

• Only affects the dynamo frontend profiling path (any backend behind it: sglang, vllm). The sglang native-frontend branch (/start_profile) is unchanged.
• TRT-LLM is unaffected (it profiles via TLLM_PROFILE_START_STOP, no HTTP call).
• No effect on non-profiling runs — this code only runs when profiling: is enabled.
• Requires Dynamo ≥ #10347. Older Dynamo served /engine/start_profile; pairing this with a pre-#10347 Dynamo would 404. In practice any Dynamo new enough to also carry the sglang ProfileReq body fix (fix(sglang): support profile request object API ai-dynamo/dynamo#11199, 2026-07-06) is already ≥ #10347, so the two go together.

[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
⚠️ Please upload report for BASE (main@f6eb42a). Learn more about missing BASE report.

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #264   +/-   ##
=======================================
  Coverage        ?   67.21%           
=======================================
  Files           ?       69           
  Lines           ?     9040           
  Branches        ?        0           
=======================================
  Hits            ?     6076           
  Misses          ?     2964           
  Partials        ?        0           

☔ View full report in Codecov by Harness.
📢 Have feedback on the report? Share it here.

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.