ai/live: Read JSONL from a time delimited data channel.

[j0sh]

Builds on top of #3705 and #3689

Two missing pieces:

1. runner: add data_url to route/pipeline and codegen ai-runner#710 still needs to be updated to emit JSONL over time based segments.
2. Signaling whether the data channel should even be created, since most live-video-to-video workflows will not have a data return channel. This is easy to check on the gateway side (if the data channel URL is empty, don't create the subscription) but still TBD on the orchestrator side.

[codecov]

Codecov Report

❌ Patch coverage is 2.80899% with 173 lines in your changes missing coverage. Please review.
✅ Project coverage is 31.58963%. Comparing base (99e4fde) to head (c8c97ca).

Files with missing lines	Patch %	Lines
server/ai_live_video.go	0.00000%	103 Missing ⚠️
server/ai_mediaserver.go	7.24638%	63 Missing and 1 partial ⚠️
server/ai_http.go	0.00000%	6 Missing ⚠️

Additional details and impacted files

@@                 Coverage Diff                 @@
##              master       #3706         +/-   ##
===================================================
- Coverage   31.68826%   31.58963%   -0.09863%     
===================================================
  Files            158         158                 
  Lines          47617       47791        +174     
===================================================
+ Hits           15089       15097          +8     
- Misses         31632       31798        +166     
  Partials         896         896                 

Files with missing lines	Coverage Δ
ai/worker/runner.gen.go	7.23104% <ø> (ø)
core/livepeernode.go	60.22099% <ø> (ø)
server/ai_process.go	1.65975% <ø> (ø)
server/ai_http.go	9.58084% <0.00000%> (-0.08683%)	⬇️
server/ai_mediaserver.go	4.82880% <7.24638%> (+0.16027%)	⬆️
server/ai_live_video.go	0.00000% <0.00000%> (ø)

... and 3 files with indirect coverage changes

---

Continue to review full report in Codecov by Sentry.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update 99e4fde...c8c97ca. Read the comment docs.

Files with missing lines	Coverage Δ
ai/worker/runner.gen.go	7.23104% <ø> (ø)
core/livepeernode.go	60.22099% <ø> (ø)
server/ai_process.go	1.65975% <ø> (ø)
server/ai_http.go	9.58084% <0.00000%> (-0.08683%)	⬇️
server/ai_mediaserver.go	4.82880% <7.24638%> (+0.16027%)	⬆️
server/ai_live_video.go	0.00000% <0.00000%> (ø)

... and 3 files with indirect coverage changes

🚀 New features to boost your workflow:

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