[FLINK-40034][runtime-web] Refresh web-dashboard lint tooling to prettier 3 and stylelint 17

[spuru9]

What is the purpose of the change

Bring the web-dashboard lint tooling current, per FLINK-40034:

• prettier 2 -> 3, eslint-plugin-prettier 4 -> 5
• stylelint 14 -> 17 + config cascade: stylelint-config-standard -> 40,
  stylelint-config-hudochenkov -> 13, stylelint-prettier -> 5; drops the
  now-unused (and stylelint-17-incompatible) stylelint-config-prettier

Jira: https://issues.apache.org/jira/browse/FLINK-40034

Brief change log

• Bumped the prettier/eslint-plugin-prettier/stylelint dependency cascade in package.json.
• stylelint-config-standard 40 adds several CSS-only rules that misfire on Less syntax, so .stylelintrc.js disables/adjusts them:
  • declaration-property-value-no-unknown, declaration-property-value-keyword-no-deprecated: otherwise flag valid Less-specific values as unknown.
  • import-notation: 'string': the default 'url' rewrites @import "x" to @import url("x"), which breaks Less inlining.
  • color-function-alias-notation: disabled after discovering it rewrites rgba(...) to a 4-argument rgb(...), which is valid modern CSS but silently drops the alpha channel when compiled through Less's built-in 3-argument rgb() function (verified via a production build: rgba(0, 0, 0, 0.8) compiled to opaque #000 before this fix).
• Ran npm run lint:fix and committed the resulting mechanical formatting diff (constructor parameter wrapping, lowercase doctype, a few Less property reorderings/shorthands) as a separate, isolated commit for easy review.
• Verified NOTICE regeneration produces no changes for this bump (prettier/eslint-plugin-prettier/stylelint are devDependencies, not reflected in NOTICE).

Angular's new built-in control-flow syntax (@if/@for) is not used anywhere in this codebase yet (still on *ngIf/*ngFor); that migration is deferred to a dedicated follow-up, per the existing comment in eslint.config.js. This PR only lands the tooling/config prerequisites.

Verifying this change

• npm run lint (cold cache) passes cleanly.
• npm run build succeeds; confirmed via the compiled CSS output that the color-function-alias-notation fix preserves the alpha channel (rgba(0,0,0,0.8) compiles to #000c, not opaque #000).
• npm run ci-check passes end-to-end.

Does this pull request potentially affect one of the following parts:

• Dependencies (does it add or upgrade a dependency): yes, devDependencies only (prettier, eslint-plugin-prettier, stylelint, and stylelint config packages); no production dependency changes.
• The public API, i.e., is any changed class annotated with @Public(Evolving): no
• The serializers: no
• The runtime per-record code paths (performance sensitive): no
• Anything that affects deployment or recovery: JobManager (and its components), Checkpointing, Kubernetes/Yarn, ZooKeeper: no
• The S3 file system connector: no

Documentation

• Does this pull request introduce a new feature? no

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Was generative AI tooling used to co-author this PR?

• Yes (Claude Code)

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CI report:

• d6371ec Azure: SUCCESS

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