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 88.63%. Comparing base (5021bc6) to head (84fff17).

Additional details and impacted files

@@             Coverage Diff              @@
##               main    #7594      +/-   ##
============================================
- Coverage     88.63%   88.63%   -0.01%     
  Complexity     4346     4346              
============================================
  Files          1177     1177              
  Lines         46894    46894              
  Branches       5229     5229              
============================================
- Hits          41566    41564       -2     
  Misses         3568     3568              
- Partials       1760     1762       +2     

Flag	Coverage Δ
access-control-service	70.00% <ø> (ø)
agent-service	98.62% <ø> (ø)
amber	84.71% <ø> (-0.01%)	⬇️
computing-unit-managing-service	60.38% <ø> (ø)
config-service	77.31% <ø> (ø)
file-service	69.05% <ø> (ø)
frontend	89.98% <ø> (-0.01%)	⬇️
notebook-migration-service	78.89% <ø> (ø)
pyamber	97.52% <ø> (ø)
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 · 🔴 7 worse · ⚪ 8 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	347	0.212	28,522/34,455/34,455 us	🔴 +24.7% / 🔴 +126.5%
🔴	bs=100 sw=10 sl=64	770	0.47	124,043/193,061/193,061 us	🔴 +13.8% / 🔴 +78.6%
⚪	bs=1000 sw=10 sl=64	907	0.553	1,103,736/1,179,255/1,179,255 us	⚪ within ±5% / 🔴 +13.6%

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	347 tuples/sec	418 tuples/sec	784.3 tuples/sec	-17.0%	-55.8%
bs=10 sw=10 sl=64	MB/s	0.212 MB/s	0.255 MB/s	0.479 MB/s	-16.9%	-55.7%
bs=10 sw=10 sl=64	p50	28,522 us	22,866 us	12,590 us	+24.7%	+126.5%
bs=10 sw=10 sl=64	p95	34,455 us	33,176 us	15,991 us	+3.9%	+115.5%
bs=10 sw=10 sl=64	p99	34,455 us	33,176 us	18,694 us	+3.9%	+84.3%
bs=100 sw=10 sl=64	throughput	770 tuples/sec	817 tuples/sec	1,002 tuples/sec	-5.8%	-23.2%
bs=100 sw=10 sl=64	MB/s	0.47 MB/s	0.499 MB/s	0.612 MB/s	-5.8%	-23.1%
bs=100 sw=10 sl=64	p50	124,043 us	118,164 us	101,285 us	+5.0%	+22.5%
bs=100 sw=10 sl=64	p95	193,061 us	169,697 us	108,068 us	+13.8%	+78.6%
bs=100 sw=10 sl=64	p99	193,061 us	169,697 us	118,235 us	+13.8%	+63.3%
bs=1000 sw=10 sl=64	throughput	907 tuples/sec	915 tuples/sec	1,030 tuples/sec	-0.9%	-11.9%
bs=1000 sw=10 sl=64	MB/s	0.553 MB/s	0.558 MB/s	0.629 MB/s	-0.9%	-12.0%
bs=1000 sw=10 sl=64	p50	1,103,736 us	1,090,278 us	991,882 us	+1.2%	+11.3%
bs=1000 sw=10 sl=64	p95	1,179,255 us	1,146,668 us	1,038,496 us	+2.8%	+13.6%
bs=1000 sw=10 sl=64	p99	1,179,255 us	1,146,668 us	1,068,265 us	+2.8%	+10.4%

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
0,10,10,64,20,576.23,200,128000,347,0.212,28521.81,34455.44,34455.44
1,100,10,64,20,2598.67,2000,1280000,770,0.470,124043.19,193060.73,193060.73
2,1000,10,64,20,22055.52,20000,12800000,907,0.553,1103736.12,1179255.49,1179255.49

[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.