[ZEPPELIN-6668] Add notebook route benchmark contract

[voidmatcha]

What is this PR for?

Add a reproducible benchmark contract for the notebook route, without committing baseline numbers (a follow-up records them).

• Fixture: 100 paragraphs (80 TEXT, 10 TABLE, 10 collapsed), pinned by SHA-256
• Ready condition: action bar visible, 100 paragraph containers, first Monaco editor attached
• Runs: 10 cold (new context) and 10 warm (after one unrecorded prime), with raw samples, median, and p95
• Bundles: raw and gzip sizes of the Angular entry chunks and React remoteEntry.js

Runtime metrics cover the Angular route only. The benchmark is excluded from the normal E2E run.

Most of the diff (3,319 of 3,957 added lines) is the fixture JSON. It is data, pinned by SHA-256 and checked for composition by validateFixture, so it does not need a line-by-line review. The code to review is about 590 lines under e2e/performance/, e2e/models/notebook-performance-page.ts, test/notebook-baseline.spec.ts and playwright.performance.config.js.

What type of PR is it?

Improvement

Todos

• Add a hash-pinned benchmark fixture
• Add the Playwright performance runner
• Validate the benchmark contract with unit tests

What is the Jira issue?

ZEPPELIN-6668

How should this be tested?

cd zeppelin-web-angular
npm run test:shell -- test/notebook-baseline.spec.ts
# against an isolated Zeppelin serving the `npm run build` output
PLAYWRIGHT_BASE_URL=http://localhost:8080 PERF_NOTEBOOK_DISPOSABLE=1 PERF_NOTEBOOK_DRY_RUN=1 npm run perf:notebook-baseline

A local dry run passes (1 cold + 1 warm, every summary field recorded). Use localhost: the server rejects a 127.0.0.1 WebSocket origin unless zeppelin.server.allowed.origins is set.

Screenshots (if appropriate)

N/A

Questions:

• Does the license files need to update? No
• Is there breaking changes for older versions? No
• Does this needs documentation? Yes - e2e/performance/README.md

[voidmatcha]

Some context the description leaves out:

Why this PR is needed. This is the first child of ZEPPELIN-6667, part of the notebook migration in ZEPPELIN-6627. The planned route host that mounts React at the notebook URL adds a mount path to that route, even while Angular stays the default, so a measurement taken after it lands no longer describes today's Angular path. This PR fixes the fixture, ready condition and output schema first, so a follow-up can record the Angular baseline under the same contract before that change.

Fixture. ZEPPELIN-6668 fixes it as a versioned note file with exactly 100 paragraphs. It is committed rather than generated so that every run, including later baselines, imports the same bytes, and its SHA-256 is recorded in every output. Changing it requires updating fixtureSha256 in e2e/performance/notebook-baseline.ts. The reviewable code is the ~590 lines outside it.

Cold runs. Each cold run starts with an empty browser HTTP cache, as ZEPPELIN-6668 requires; OS and server caches are not flushed.

[tbonelee]

Merged into master