feat(otap-dataflow): [WIP] add live internal log streaming to the admin UI

[lalitb]

Description

This PR adds live internal log viewing to the embedded admin UI.

It introduces:

• a WebSocket log stream endpoint for retained internal logs
• server-side pause/resume, backfill, and filtering for the stream
• an “Internal Logs” panel in the admin UI

Implementation notes:

• log_tap now supports live subscribers in addition to retained-log queries
• the stream reuses the admin log schema used by /api/v1/telemetry/logs
• the log panel remains disconnected by default and only opens the stream when the user explicitly clicks Connect

User-facing behavior:

• view internal logs live in the admin UI
• pause/resume server-side delivery
• resync from retained logs after drops
• filter by minimum level and text

When admin UI opened, the log panel is disabled.

When enabled:

[codecov]

Codecov Report

❌ Patch coverage is 61.47705% with 193 lines in your changes missing coverage. Please review.
✅ Project coverage is 88.09%. Comparing base (5868ff1) to head (0316fa5).

❌ Your patch check has failed because the patch coverage (61.47%) is below the target coverage (70.00%). You can increase the patch coverage or adjust the target coverage.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #2620      +/-   ##
==========================================
- Coverage   88.14%   88.09%   -0.06%     
==========================================
  Files         633      633              
  Lines      235806   236291     +485     
==========================================
+ Hits       207862   208153     +291     
- Misses      27420    27614     +194     
  Partials      524      524              

Components	Coverage Δ
otap-dataflow	89.77% <61.47%> (-0.08%)	⬇️
query_abstraction	80.61% <ø> (ø)
query_engine	90.74% <ø> (ø)
otel-arrow-go	52.45% <ø> (ø)
quiver	92.27% <ø> (ø)

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[lquerel]

Could you add a screenshot showing the controls to display / hide the log tap panel.

[lalitb]

Could you add a screenshot showing the controls to display / hide the log tap panel.

I added that now. This PR originally did not include a separate show/hide control for the Internal Logs panel, but it does now, and I’ve also added screenshots showing the display/hide control and the panel state.