Add Apache Gluten/Velox support to DataFlint UI

[menishmueli]

Summary

• Add full Gluten/Velox node type support to the DataFlint SQL plan flow view: node classification, friendly display names, Velox-native metrics (aggregation/filter/sort/window time, peak memory, spill), and accelerator badges (Velox, Photon, RAPIDS, DataFusion)
• Fix stage identification for Gluten's WholeStageCodegenTransformer by inferring codegen-to-node mapping from node ID ordering, handling AQE codegen renumbering, and propagating stages through Gluten-specific boundary nodes
• Add Docker environment and Scala example app for running Gluten/Velox on Spark 3.5 with DataFlint, including automation script

Test plan

• 93 UI unit tests pass (17 suites), including new GlutenStageAssignment.spec.ts with real fixture data
• Visually verify all 16 SQL queries at localhost:4000 with the Gluten example app running in Docker
• Verify exchange nodes split correctly between stages (write/read)
• Verify Window nodes show partition-by and sort-by columns
• Verify accelerator badges appear on Velox nodes and not on standard Spark nodes
• Verify no regressions on standard (non-Gluten) Spark plans

[CLAassistant]

Thank you for your submission! We really appreciate it. Like many open source projects, we ask that you sign our Contributor License Agreement before we can accept your contribution.
_{You have signed the CLA already but the status is still pending? Let us recheck it.}

[menishmueli]

Screenshots

Status Page — GlutenVeloxExample with 16 SQL Queries

The DataFlint status page correctly identifies the Gluten/Velox application.

GroupBy Aggregation (SQL 3) — Two stages with split exchange

Shows Stage 5 (write side) and Stage 7 (read side) with the ColumnarExchange visually split. All Velox-accelerated nodes have orange Velox badges. Native metrics like Aggregation Time and Peak Memory are displayed.

Window Functions (SQL 10) — Three stages with window partition fields

Shows Stage 47, Stage 49, and Stage 52 with two split ColumnarExchange nodes. Window nodes display Partition Fields (play_name), Sort Fields, and Select Fields parsed from the physical plan.

---

Note: To view live screenshots, run ./docker/gluten/run-gluten-example.sh and visit http://localhost:4000