feat(operator-demo-video): add DemoVideoGenerator module and Playwright automation foundation

[xuang7]

What changes were proposed in this PR?

This PR adds the foundation for an operator demo video generator: a Playwright-based tool that records a short demo video per operator, to be linked from the operator docs under docs/reference/operators/.

Changes:

• A new DemoVideoGenerator sbt module at docs/operator-demo-videos/ with the Playwright dependency. It is standalone. It compiles without the rest of the build.
• The automation abstractions the tool is built from: fluent builders that accumulate named steps (ControllerBuilder/ControllerStep), a two-phase per-operator script trait (prepare = unrecorded scaffolding, execute = the recorded demo), and a fake on-screen cursor so recordings show where the automation is clicking.
• Adds the recording configuration in TestDataConfig (base URL, viewport and video size, pacing, output directory); later PRs will add more defaults such as the datasets and template workflows.
• Excludes docs/operator-demo-videos/ from the docs-to-website sync workflow: the module is build tooling, not docs content, so its sources are never published to the website and module-only pushes do not trigger a site sync.

Follow-up PRs add the UI controllers (login, navigation, drag-and-connect, form filling, execution), per-operator sample values, and the generator and runner that make the tool runnable end-to-end.

Any related issues, documentation, discussions?

Closes #7519

How was this PR tested?

No behavior change to any existing module. sbt DemoVideoGenerator/compile, scalafmtCheck, and scalafix --check all pass.

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

Generated-by: Claude Code (Claude Fable 5)

[github-actions]

Automated Reviewer Suggestions

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

• Contributors with relevant context: @kunwp1
  You can notify them by mentioning @kunwp1 in a comment.

[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 89.65%. Comparing base (5021bc6) to head (f6d6f0b).
⚠️ Report is 30 commits behind head on main.

Additional details and impacted files

@@             Coverage Diff              @@
##               main    #7594      +/-   ##
============================================
+ Coverage     88.63%   89.65%   +1.01%     
- Complexity     4346     4398      +52     
============================================
  Files          1177     1177              
  Lines         46894    46996     +102     
  Branches       5229     5268      +39     
============================================
+ Hits          41566    42135     +569     
+ Misses         3568     3095     -473     
- Partials       1760     1766       +6     

Flag	Coverage Δ
access-control-service	70.00% <ø> (ø)
agent-service	98.62% <ø> (+<0.01%)	⬆️
amber	86.35% <ø> (+1.63%)	⬆️
computing-unit-managing-service	72.46% <ø> (+12.07%)	⬆️
config-service	77.31% <ø> (ø)
file-service	68.90% <ø> (-0.15%)	⬇️
frontend	90.67% <ø> (+0.68%)	⬆️
notebook-migration-service	78.89% <ø> (ø)
pyamber	97.57% <ø> (+0.05%)	⬆️
workflow-compiling-service	57.89% <ø> (ø)

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[xuang7]

Could you take a look when you're available? Thanks! @carloea2

[github-actions]

⚠️ Benchmark changes need a look

🟢 0 better · 🔴 10 worse · ⚪ 5 noise (<±5%) · 0 without baseline

Compared against main 5021bc6 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	374	0.228	25,941/32,968/32,968 us	🔴 +16.3% / 🔴 +103.6%
🔴	bs=100 sw=10 sl=64	765	0.467	127,211/166,312/166,312 us	🔴 +9.2% / 🔴 +54.6%
⚪	bs=1000 sw=10 sl=64	902	0.551	1,108,596/1,175,300/1,175,300 us	⚪ within ±5% / 🔴 +13.4%

Baseline details

Latest main 5021bc6 from same runner

config	metric	PR	latest main	7d avg	Δ latest	Δ 7d
bs=10 sw=10 sl=64	throughput	374 tuples/sec	437 tuples/sec	774.89 tuples/sec	-14.4%	-51.7%
bs=10 sw=10 sl=64	MB/s	0.228 MB/s	0.266 MB/s	0.473 MB/s	-14.3%	-51.8%
bs=10 sw=10 sl=64	p50	25,941 us	22,330 us	12,738 us	+16.2%	+103.6%
bs=10 sw=10 sl=64	p95	32,968 us	28,336 us	16,348 us	+16.3%	+101.7%
bs=10 sw=10 sl=64	p99	32,968 us	28,336 us	18,848 us	+16.3%	+74.9%
bs=100 sw=10 sl=64	throughput	765 tuples/sec	815 tuples/sec	1,005 tuples/sec	-6.1%	-23.9%
bs=100 sw=10 sl=64	MB/s	0.467 MB/s	0.498 MB/s	0.613 MB/s	-6.2%	-23.8%
bs=100 sw=10 sl=64	p50	127,211 us	119,503 us	100,970 us	+6.5%	+26.0%
bs=100 sw=10 sl=64	p95	166,312 us	152,349 us	107,605 us	+9.2%	+54.6%
bs=100 sw=10 sl=64	p99	166,312 us	152,349 us	116,429 us	+9.2%	+42.8%
bs=1000 sw=10 sl=64	throughput	902 tuples/sec	910 tuples/sec	1,030 tuples/sec	-0.9%	-12.5%
bs=1000 sw=10 sl=64	MB/s	0.551 MB/s	0.555 MB/s	0.629 MB/s	-0.7%	-12.4%
bs=1000 sw=10 sl=64	p50	1,108,596 us	1,091,248 us	991,433 us	+1.6%	+11.8%
bs=1000 sw=10 sl=64	p95	1,175,300 us	1,177,492 us	1,036,668 us	-0.2%	+13.4%
bs=1000 sw=10 sl=64	p99	1,175,300 us	1,177,492 us	1,070,470 us	-0.2%	+9.8%

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
0,10,10,64,20,534.79,200,128000,374,0.228,25941.20,32968.48,32968.48
1,100,10,64,20,2614.41,2000,1280000,765,0.467,127211.21,166311.50,166311.50
2,1000,10,64,20,22173.07,20000,12800000,902,0.551,1108596.07,1175300.23,1175300.23

[carloea2]

The cursor setup after navigation does not run. The startup script only defines a function. Please pass the script body or call the function.