Update Stone, dependencies, Node, and CI

[AndreyVMarkelov]

Summary

• update the Stone submodule to v3.5.2 and adapt code generation to Stone's output-root validation
• upgrade the active npm dependencies, React, TypeScript toolchain, and Node runtime baseline
• replace the vulnerable Browserify/Gulp/Mocha/NYC stack with esbuild, Node's test runner, and c8
• modernize CI, coverage, GitHub Pages deployment, and spec-update workflows
• pin Node 24.18.0 LTS and use the same version in every workflow

Impact

The project now installs reproducibly from the public npm registry, builds on Node 24, and has zero npm audit vulnerabilities. CI failures are blocking and cover linting, type checking, unit tests, and production builds.

The API spec submodule is intentionally unchanged in this PR and remains at the repository's existing commit 3d1080a; generated endpoints were validated with the updated Stone version against that pinned spec.

Validation

• clean npm ci with Node 24.18.0
• npm run lint
• npm run typecheck
• npm test
• npm run build
• npm run coverage:unit
• ./codegen/run_codegen.sh (repeatable)
• actionlint
• git diff --check
• npm audit: 0 vulnerabilities

[codecov]

Codecov Report

❌ Patch coverage is 7.54717% with 49 lines in your changes missing coverage. Please review.
✅ Project coverage is 11.08%. Comparing base (7266d7b) to head (b206e41).

Files with missing lines	Patch %	Lines
src/endpoints.ts	0.00%	40 Missing ⚠️
src/main.ts	0.00%	9 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff            @@
##            main     #333      +/-   ##
=========================================
+ Coverage   5.83%   11.08%   +5.24%     
=========================================
  Files          6        6              
  Lines       1114     5568    +4454     
  Branches     120        4     -116     
=========================================
+ Hits          65      617     +552     
- Misses      1049     4951    +3902     

Flag	Coverage Δ
unit	11.08% <7.54%> (+5.24%)	⬆️

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