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

[Ma77Ball]

What changes were proposed in this PR?

First complete signal: log search through the gateway plus a UI panel to drive it.
Backend:

• Logs query builder and response parsers (parseLogs, parseLogSources), applying per-field redaction.
• LogsResource exposing log search and the source-facets endpoint, registered in TexeraWebApplication.
  Frontend:
• Logs panel with time-window, service, workflow, computing-unit, execution, level, and free-text filters, server-side paging, and sources-backed autofill.

Any related issues, documentation, or discussions?

Closes: #5371
Part of #4070. Stacked on #5378.

How was this PR tested?

• Backend specs for the logs query builder and response parsers; sbt scalafmtCheckAll passes.
• Frontend logs-panel and service 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 63.93636% with 612 lines in your changes missing coverage. Please review.
✅ Project coverage is 55.29%. Comparing base (6d31f46) to head (6f9292a).
⚠️ Report is 52 commits behind head on main.

Files with missing lines	Patch %	Lines
...observability/gateway/ObservabilityResources.scala	0.00%	165 Missing ⚠️
...observability/logs-panel/logs-panel.component.html	56.71%	58 Missing ⚠️
...apache/texera/web/observability/gateway/dtos.scala	70.32%	48 Missing and 6 partials ⚠️
...ala/org/apache/texera/observability/OtelInit.scala	63.30%	43 Missing and 8 partials ⚠️
...texera/web/observability/gateway/AuditLogger.scala	0.00%	41 Missing ⚠️
...xera/web/observability/gateway/ScopeResolver.scala	19.44%	27 Missing and 2 partials ⚠️
...era/web/observability/gateway/GatewayContext.scala	0.00%	19 Missing ⚠️
...a/org/apache/texera/web/TexeraWebApplication.scala	0.00%	16 Missing ⚠️
...r/observability/logs-panel/logs-panel.component.ts	85.18%	3 Missing and 13 partials ⚠️
...ra/web/observability/gateway/ResponseParsers.scala	78.78%	8 Missing and 6 partials ⚠️
... and 27 more

Additional details and impacted files

@@             Coverage Diff              @@
##               main    #5379      +/-   ##
============================================
+ Coverage     53.86%   55.29%   +1.43%     
- Complexity     2756     3018     +262     
============================================
  Files          1099     1144      +45     
  Lines         42541    44603    +2062     
  Branches       4577     4924     +347     
============================================
+ Hits          22916    24665    +1749     
- Misses        18290    18469     +179     
- Partials       1335     1469     +134     

Flag	Coverage Δ		*Carryforward flag
access-control-service	70.14% <100.00%> (-0.30%)	⬇️
agent-service	34.36% <ø> (ø)		Carriedforward from f6bf45d
amber	57.46% <58.20%> (+2.26%)	⬆️
computing-unit-managing-service	0.00% <0.00%> (-1.66%)	⬇️
config-service	50.76% <40.00%> (-5.95%)	⬇️
file-service	58.88% <68.96%> (+1.81%)	⬆️
frontend	49.28% <77.93%> (+1.22%)	⬆️
notebook-migration-service	78.57% <ø> (?)
pyamber	90.15% <100.00%> (+0.02%)	⬆️	Carriedforward from f6bf45d
python	90.76% <ø> (-0.04%)	⬇️	Carriedforward from f6bf45d
workflow-compiling-service	54.74% <ø> (-3.96%)	⬇️

*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.