feat(observability): profiles end-to-end (gateway + UI panel)

[Ma77Ball]

What changes were proposed in this PR?

Continuous-profiling retrieval through the gateway plus a flame-graph UI panel.
Backend:

• ParcaClient: gRPC-Web client to the Parca server, with a profiles query builder and parseProfiles.
• ProfilesResource exposing scoped profile queries (optional workflow and execution id), registered in TexeraWebApplication.
  Frontend:
• Profiles panel with a flame-chart component, scoped by workflow and execution id, with explicit empty states for "no samples yet" and for environments where profiling is disabled.

Any related issues, documentation, or discussions?

Closes: #5374
Part of #4070. Stacked on #5381.

How was this PR tested?

• Backend specs for ParcaClient, the profiles query builder, and the parser; sbt scalafmtCheckAll passes.
• Frontend profiles-panel and flame-chart specs; prettier-eslint and eslint pass.
• Compile and the full test suites run in this PR's CI.

Was this PR authored or co-authored using generative AI tooling?

Co-authored with Claude Opus 4.8 in compliance with ASF

[codecov-commenter]

Codecov Report

❌ Patch coverage is 59.08892% with 934 lines in your changes missing coverage. Please review.
✅ Project coverage is 55.22%. Comparing base (7a38b6c) to head (5e8640f).
⚠️ Report is 5 commits behind head on main.

Files with missing lines	Patch %	Lines
...observability/gateway/ObservabilityResources.scala	0.00%	314 Missing ⚠️
...texera/web/observability/gateway/ParcaClient.scala	40.10%	98 Missing and 20 partials ⚠️
...observability/logs-panel/logs-panel.component.html	56.71%	58 Missing ⚠️
...ala/org/apache/texera/observability/OtelInit.scala	63.30%	43 Missing and 8 partials ⚠️
...apache/texera/web/observability/gateway/dtos.scala	76.28%	40 Missing and 6 partials ⚠️
...texera/web/observability/gateway/AuditLogger.scala	0.00%	41 Missing ⚠️
...xera/web/observability/gateway/ScopeResolver.scala	19.44%	27 Missing and 2 partials ⚠️
...ra/web/observability/gateway/ResponseParsers.scala	77.96%	10 Missing and 16 partials ⚠️
...rvability/traces-panel/traces-panel.component.html	42.10%	22 Missing ⚠️
...era/web/observability/gateway/GatewayContext.scala	0.00%	21 Missing ⚠️
... and 30 more

Additional details and impacted files

@@             Coverage Diff              @@
##               main    #5382      +/-   ##
============================================
+ Coverage     54.89%   55.22%   +0.32%     
- Complexity     2962     2996      +34     
============================================
  Files          1117     1154      +37     
  Lines         43133    45602    +2469     
  Branches       4648     5098     +450     
============================================
+ Hits          23680    25184    +1504     
- Misses        18064    18898     +834     
- Partials       1389     1520     +131     

Flag	Coverage Δ		*Carryforward flag
access-control-service	70.14% <100.00%> (+0.14%)	⬆️
agent-service	34.36% <ø> (ø)		Carriedforward from 6c77d4a
amber	56.37% <48.95%> (-0.70%)	⬇️
computing-unit-managing-service	0.00% <0.00%> (ø)
config-service	50.76% <0.00%> (-0.80%)	⬇️
file-service	58.88% <0.00%> (-0.15%)	⬇️
frontend	49.94% <80.24%> (+1.33%)	⬆️
notebook-migration-service	78.57% <ø> (ø)
pyamber	91.18% <ø> (+0.98%)	⬆️	Carriedforward from 6c77d4a
python	90.76% <ø> (ø)		Carriedforward from 6c77d4a
workflow-compiling-service	54.74% <0.00%> (-0.41%)	⬇️

*This pull request uses carry forward flags. Click here to find out more.

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[github-actions]

Automated Reviewer Suggestions

Based on the git blame history of the changed files, we recommend the following reviewers:

• Contributors with relevant context: @bobbai00, @aicam, @Yicong-Huang
  You can notify them by mentioning @bobbai00, @aicam, @Yicong-Huang in a comment.