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

[Ma77Ball]

What changes were proposed in this PR?

Distributed-trace retrieval through the gateway plus a trace-tree UI panel.
Backend:

• Trace query builder and parseTraces.
• TracesResource exposing trace retrieval by id, with id validation and scope enforcement at the gateway.
  Frontend:
• Traces panel rendering spans as a tree built from parent-span relationships, with pivot-from-log so a log row can open its trace directly. Span fields are bound with text interpolation only.

Any related issues, documentation, or discussions?

Closes: #5373
Part of #4070. Stacked on #5380.

How was this PR tested?

• Backend specs for the trace query builder and parser; sbt scalafmtCheckAll passes.
• Frontend traces-panel specs, including the span-tree builder; 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 63.37262% with 808 lines in your changes missing coverage. Please review.
✅ Project coverage is 53.23%. Comparing base (7e9cabf) to head (f2f9e93).
⚠️ Report is 24 commits behind head on main.

Files with missing lines	Patch %	Lines
...observability/gateway/ObservabilityResources.scala	0.00%	224 Missing ⚠️
...nt/user/list-item/card-item/card-item.component.ts	47.23%	76 Missing and 10 partials ⚠️
...observability/logs-panel/logs-panel.component.html	56.92%	55 Missing and 1 partial ⚠️
...ala/org/apache/texera/observability/OtelInit.scala	63.30%	43 Missing and 8 partials ⚠️
...apache/texera/web/observability/gateway/dtos.scala	75.39%	40 Missing and 7 partials ⚠️
...texera/web/observability/gateway/AuditLogger.scala	0.00%	41 Missing ⚠️
.../user/list-item/card-item/card-item.component.html	56.52%	38 Missing and 2 partials ⚠️
...xera/web/observability/gateway/ScopeResolver.scala	19.44%	27 Missing and 2 partials ⚠️
...era/web/observability/gateway/GatewayContext.scala	0.00%	19 Missing ⚠️
...rvability/traces-panel/traces-panel.component.html	44.11%	19 Missing ⚠️
... and 29 more

Additional details and impacted files

@@             Coverage Diff              @@
##               main    #5381      +/-   ##
============================================
+ Coverage     52.87%   53.23%   +0.35%     
- Complexity     2509     2665     +156     
============================================
  Files          1073     1120      +47     
  Lines         41382    43894    +2512     
  Branches       4444     4864     +420     
============================================
+ Hits          21882    23368    +1486     
- Misses        18214    19133     +919     
- Partials       1286     1393     +107     

Flag	Coverage Δ		*Carryforward flag
access-control-service	70.91% <100.00%> (+6.30%)	⬆️
agent-service	34.36% <ø> (ø)		Carriedforward from fed8677
amber	53.14% <60.10%> (-0.47%)	⬇️
computing-unit-managing-service	1.65% <ø> (ø)
config-service	56.71% <ø> (ø)
file-service	57.06% <ø> (ø)
frontend	48.76% <68.14%> (+1.45%)	⬆️
pyamber	90.73% <100.00%> (+0.01%)	⬆️	Carriedforward from fed8677
python	90.73% <ø> (-0.03%)	⬇️	Carriedforward from fed8677
workflow-compiling-service	58.69% <ø> (ø)

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

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[github-actions]

⚠️ Benchmark changes need a look

🟢 4 better · 🔴 2 worse · ⚪ 9 noise (<±5%) · 0 without baseline

Compared against main b8859b4 benchmarked on this same runner, so the delta is largely free of cross-runner hardware noise. The "7d avg" column still reflects the gh-pages dashboard. Treat <±5% as noise unless repeated.

Dashboard · Run

	config	throughput	MB/s	latency	max Δ latest / 7d
🟢	bs=10 sw=10 sl=64	395	0.241	25,389/33,397/33,397 us	🟢 -39.7% / 🔴 +6.7%
⚪	bs=100 sw=10 sl=64	813	0.496	121,606/150,711/150,711 us	⚪ within ±5% / 🔴 -8.9%
🔴	bs=1000 sw=10 sl=64	921	0.562	1,081,066/1,180,232/1,180,232 us	🔴 +6.1% / 🔴 +15.4%

Baseline details

Latest main b8859b4 from same runner

config	metric	PR	latest main	7d avg	Δ latest	Δ 7d
bs=10 sw=10 sl=64	throughput	395 tuples/sec	365 tuples/sec	410.82 tuples/sec	+8.2%	-3.9%
bs=10 sw=10 sl=64	MB/s	0.241 MB/s	0.223 MB/s	0.251 MB/s	+8.1%	-3.9%
bs=10 sw=10 sl=64	p50	25,389 us	25,990 us	23,785 us	-2.3%	+6.7%
bs=10 sw=10 sl=64	p95	33,397 us	55,369 us	34,980 us	-39.7%	-4.5%
bs=10 sw=10 sl=64	p99	33,397 us	55,369 us	34,980 us	-39.7%	-4.5%
bs=100 sw=10 sl=64	throughput	813 tuples/sec	824 tuples/sec	891.94 tuples/sec	-1.3%	-8.9%
bs=100 sw=10 sl=64	MB/s	0.496 MB/s	0.503 MB/s	0.544 MB/s	-1.4%	-8.9%
bs=100 sw=10 sl=64	p50	121,606 us	121,100 us	112,277 us	+0.4%	+8.3%
bs=100 sw=10 sl=64	p95	150,711 us	151,756 us	139,802 us	-0.7%	+7.8%
bs=100 sw=10 sl=64	p99	150,711 us	151,756 us	139,802 us	-0.7%	+7.8%
bs=1000 sw=10 sl=64	throughput	921 tuples/sec	932 tuples/sec	1,041 tuples/sec	-1.2%	-11.5%
bs=1000 sw=10 sl=64	MB/s	0.562 MB/s	0.569 MB/s	0.635 MB/s	-1.2%	-11.6%
bs=1000 sw=10 sl=64	p50	1,081,066 us	1,071,888 us	972,714 us	+0.9%	+11.1%
bs=1000 sw=10 sl=64	p95	1,180,232 us	1,111,871 us	1,023,057 us	+6.1%	+15.4%
bs=1000 sw=10 sl=64	p99	1,180,232 us	1,111,871 us	1,023,057 us	+6.1%	+15.4%

Raw CSV

config_idx,batch_size,schema_width,string_len,num_batches,total_ms,total_tuples,total_bytes,tuples_per_sec,mb_per_sec,lat_p50_us,lat_p95_us,lat_p99_us
0,10,10,64,20,505.74,200,128000,395,0.241,25388.97,33397.08,33397.08
1,100,10,64,20,2459.70,2000,1280000,813,0.496,121606.05,150710.68,150710.68
2,1000,10,64,20,21710.01,20000,12800000,921,0.562,1081065.92,1180232.09,1180232.09