[Improve][UI] Reduce seatunnel-engine-ui node_modules size (~90 MB)

[davidzollo]

Purpose

The seatunnel-engine-ui module's node_modules directory has grown to 388 MB, with several packages either unused, miscategorised, or replaceable with lighter alternatives. This PR addresses the root causes.

Changes

1. Remove unused direct dependencies

• date-fns-tz (572 KB) — declared in dependencies but never imported anywhere in the source code.
• date-fns (36 MB) — only used for a single parse() call in detail.tsx. Replaced with native new Date(str.replace(' ', 'T')), which handles the yyyy-MM-dd HH:mm:ss format produced by the SeaTunnel backend.

2. Replace @vicons/ionicons5 (33 MB) with inline SVG components

• The package ships 2,672 files but only 4 icons were used: DesktopOutline, ListOutline, PeopleOutline, PersonOutline.
• Added src/components/icons/index.ts containing the four icons as lightweight Vue components (SVG paths copied verbatim from the original package source).
• Updated sidebar/index.tsx to import from the local file.

3. Replace sass-embedded with sass in devDependencies

• sass-embedded pulled in colorjs.io (8 MB) and rxjs (11 MB) as transitive dependencies.
• The plain sass package (JavaScript implementation, same API) has no such transitive overhead and is fully compatible with the project's SCSS files.

4. Move build-time tools to devDependencies

• tailwindcss, postcss, autoprefixer were incorrectly placed in dependencies (runtime). Moved to devDependencies (build-time only). This also enables future CI optimisation with npm install --omit=dev.

Estimated savings

Change	Saved
Remove date-fns + date-fns-tz	~36 MB
Remove @vicons/ionicons5	~33 MB
sass vs sass-embedded chain	~20 MB
Total	~90 MB

Verification

• npm install — clean install succeeds ✓
• npm run build-only — Vite production build succeeds with 3,151 modules transformed ✓

[nzw921rx]

+1 if ci pass

[DanielLeens]

Thanks for the cleanup here. I reviewed the full current head from the actual runtime path instead of only checking package.json.

What this PR fixes

• User pain: seatunnel-engine-ui carries more Node runtime/install weight than it needs for the code paths that are actually used.
• Proposed fix: move build-only packages to devDependencies, remove no-longer-used runtime packages, replace the sidebar icon dependency with local SVG components, and simplify the job-detail time parsing path.
• One-line summary: the latest head looks coherent to me, and I do not see a source-level blocker in the UI path.

Call chain I traced

npm install
  -> runtime deps only keep real runtime packages
  -> build-only deps move to devDependencies

sidebar render
  -> src/layouts/main/sidebar/index.tsx
     -> imports local icons from src/components/icons/index.ts
     -> Naive UI renders the SVG components

job detail page
  -> getJobInfo(jobId)
  -> res.createTime like "yyyy-MM-dd HH:mm:ss"
  -> new Date(res.createTime.replace(' ', 'T'))
  -> getRemainTime(...)

Findings

• I did not find any remaining direct source usage of @vicons/ionicons5, date-fns, or date-fns-tz in the UI code path touched by this PR.
• The local icon replacement is narrow and self-contained.
• The createTime parsing change keeps the same local-time interpretation that the previous date-fns parse(...) path had for this input shape.

CI status

The current Build is still red, but the failing lanes I found are backend / integration lanes such as:

• unit-test (8, ubuntu-latest)
• all-connectors-it-5
• all-connectors-it-7
• kafka-connector-it
• rocketmq-connector-it
• transform-v2-it-part-1

At the same time, Build SeaTunnel UI is skipped on this run. So based on the current evidence, I do not see a source-level reason to block this UI dependency cleanup itself.

Merge conclusion

Conclusion: can merge.

Must fix before merge

• No new source-level blocker from me on the latest head.

Keep an eye on

• The remaining red Build lanes above still need to be cleared at the PR level, but I do not have an additional code-path blocker to add from this diff.

Nice scope control on this one.