feat(dashboard): add custom cover image for workflow cards

[Ma77Ball]

What changes were proposed in this PR?

• Add a workflow_cover_image(wid, image) table (cover stored as a downscaled JPEG data URL, FK to workflow with ON DELETE CASCADE) in texera_ddl.sql plus a sql/updates/25.sql migration.
• Add access-gated GET/PUT/DELETE /workflow/{wid}/cover endpoints on WorkflowResource: read access to fetch (404 when unset), write access to set/delete, with data-URL and size validation on set.
• Add WorkflowCoverService (frontend) that downscales/re-encodes the chosen file to a small JPEG data URL before upload, fetches the cover, and clears it.
• Add hover controls on the workflow card (camera to pick an image, rollback to reset), shown only to the owner in private search; previewImage now prefers the stored cover.

Any related issues, documentation, discussions?

Closes: #5703

How was this PR tested?

• Backend: WorkflowResourceCoverSpec (uses the MockTexeraDB embedded-Postgres harness) covers all three cover endpoints: 404 when unset, set/get round-trip, read by a user with read access, upsert replace, data-URL/blank/null/size validation rejections, read- and write-access gating, no-persist on validation failure, and idempotent delete. Run sbt "WorkflowExecutionService/testOnly *WorkflowResourceCoverSpec".
• Frontend (service): WorkflowCoverService spec covers GET mapping the image, 404 resolving to undefined, DELETE being issued, and setCoverFromFile PUTting the resized data URL. Run cd frontend && yarn test --include='**/workflow-cover.service.spec.ts' --watch=false.
• Frontend (component): CardItemComponent spec covers the cover behaviors (owner-in-private-search gating, cover load on init, default-image fallback, upload success / non-image rejection / upload failure, reset success / failure). Run cd frontend && yarn test --include='**/card-item.component.spec.ts' --watch=false.
• Manual: open the dashboard in private search as a workflow owner, hover a card, click the camera icon, pick an image, expect the card preview to update; reload in another browser and expect the same cover (synced via backend).
• Manual: click the rollback icon, expect the card to revert to the default background and the cover to be gone after reload.

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 64.28571% with 40 lines in your changes missing coverage. Please review.
✅ Project coverage is 52.91%. Comparing base (dfa0434) to head (b39d019).

Files with missing lines	Patch %	Lines
...vice/user/workflow-cover/workflow-cover.service.ts	42.42%	19 Missing ⚠️
.../user/list-item/card-item/card-item.component.html	7.14%	13 Missing ⚠️
...nt/user/list-item/card-item/card-item.component.ts	76.66%	4 Missing and 3 partials ⚠️
...rce/dashboard/user/workflow/WorkflowResource.scala	97.14%	1 Missing ⚠️

Additional details and impacted files

@@             Coverage Diff              @@
##               main    #5704      +/-   ##
============================================
- Coverage     52.91%   52.91%   -0.01%     
- Complexity     2626     2635       +9     
============================================
  Files          1090     1091       +1     
  Lines         42188    42289     +101     
  Branches       4531     4544      +13     
============================================
+ Hits          22324    22376      +52     
- Misses        18555    18598      +43     
- Partials       1309     1315       +6     

Flag	Coverage Δ		*Carryforward flag
access-control-service	70.91% <ø> (ø)
agent-service	34.36% <ø> (ø)		Carriedforward from fa5fcbb
amber	53.11% <97.14%> (+0.09%)	⬆️
computing-unit-managing-service	1.65% <ø> (ø)
config-service	56.71% <ø> (ø)
file-service	57.06% <ø> (ø)
frontend	47.89% <49.35%> (-0.05%)	⬇️
pyamber	90.71% <ø> (-0.03%)	⬇️	Carriedforward from fa5fcbb
python	90.73% <ø> (ø)		Carriedforward from fa5fcbb
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

🟢 2 better · 🔴 5 worse · ⚪ 8 noise (<±5%) · 0 without baseline

Compared against main dfa0434 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	391	0.238	26,102/33,922/33,922 us	🟢 -15.1% / 🔴 +9.7%
🔴	bs=100 sw=10 sl=64	812	0.496	121,770/139,402/139,402 us	🔴 +12.5% / 🔴 -9.0%
⚪	bs=1000 sw=10 sl=64	941	0.574	1,061,990/1,151,310/1,151,310 us	⚪ within ±5% / 🔴 +12.5%

Baseline details

Latest main dfa0434 from same runner

config	metric	PR	latest main	7d avg	Δ latest	Δ 7d
bs=10 sw=10 sl=64	throughput	391 tuples/sec	393 tuples/sec	410.82 tuples/sec	-0.5%	-4.8%
bs=10 sw=10 sl=64	MB/s	0.238 MB/s	0.24 MB/s	0.251 MB/s	-0.8%	-5.1%
bs=10 sw=10 sl=64	p50	26,102 us	24,248 us	23,785 us	+7.6%	+9.7%
bs=10 sw=10 sl=64	p95	33,922 us	39,965 us	34,980 us	-15.1%	-3.0%
bs=10 sw=10 sl=64	p99	33,922 us	39,965 us	34,980 us	-15.1%	-3.0%
bs=100 sw=10 sl=64	throughput	812 tuples/sec	864 tuples/sec	891.94 tuples/sec	-6.0%	-9.0%
bs=100 sw=10 sl=64	MB/s	0.496 MB/s	0.527 MB/s	0.544 MB/s	-5.9%	-8.9%
bs=100 sw=10 sl=64	p50	121,770 us	116,343 us	112,277 us	+4.7%	+8.5%
bs=100 sw=10 sl=64	p95	139,402 us	123,872 us	139,802 us	+12.5%	-0.3%
bs=100 sw=10 sl=64	p99	139,402 us	123,872 us	139,802 us	+12.5%	-0.3%
bs=1000 sw=10 sl=64	throughput	941 tuples/sec	954 tuples/sec	1,041 tuples/sec	-1.4%	-9.6%
bs=1000 sw=10 sl=64	MB/s	0.574 MB/s	0.582 MB/s	0.635 MB/s	-1.4%	-9.7%
bs=1000 sw=10 sl=64	p50	1,061,990 us	1,049,812 us	972,714 us	+1.2%	+9.2%
bs=1000 sw=10 sl=64	p95	1,151,310 us	1,104,869 us	1,023,057 us	+4.2%	+12.5%
bs=1000 sw=10 sl=64	p99	1,151,310 us	1,104,869 us	1,023,057 us	+4.2%	+12.5%

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
0,10,10,64,20,512.09,200,128000,391,0.238,26102.42,33921.57,33921.57
1,100,10,64,20,2463.21,2000,1280000,812,0.496,121770.19,139402.28,139402.28
2,1000,10,64,20,21258.47,20000,12800000,941,0.574,1061990.33,1151309.76,1151309.76

[Ma77Ball]

/request-review @xuang7 @aglinxinyuan