Fix vitest workspace deprecation warning by migrating to projects config

[Copilot]

https://trello.com/c/7GkdzEfj/1819-20-fe-fix-vitest-workspace-deprecation-warning-by-migrating-to-projects-config

This PR addresses deprecation warnings in vitest v3 by migrating from the deprecated workspace configuration to the new projects-based setup.

Changes Made

Vitest Configuration Migration:

• Removed deprecated vitest.workspace.json file
• Created new root-level vitest.config.ts using the test.projects field
• Migrated project references: ["front/vite.config.ts", "shared-components/vitest.config.ts"]

Configuration Updates:

• Updated root tsconfig.json to include the new vitest.config.ts file
• Modified .eslintrc.cjs to support root-level TypeScript files by adding ./tsconfig.json to the project paths

Issue Resolution

The main deprecation warning was:

DEPRECATED  The workspace file is deprecated and will be removed in the next major. Please, use the `test.projects` field in the root config file instead.

This warning appeared every time pnpm test was run. The new configuration follows vitest v4 best practices and eliminates the deprecation warning.

Verification

• ✅ All frontend builds pass: pnpm -C front build and pnpm -C statviz build
• ✅ All tests pass: pnpm test runs without deprecation warnings
• ✅ ESLint and TypeScript configurations work correctly with the new setup
• ✅ No vitest-related deprecation warnings are present

The codebase is now ready for vitest v4 and uses the recommended configuration patterns.

Fixes #2258.

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[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 75.18%. Comparing base (ceb9308) to head (96c5b72).
⚠️ Report is 1 commits behind head on master.

Additional details and impacted files

@@           Coverage Diff           @@
##           master    #2298   +/-   ##
=======================================
  Coverage   75.18%   75.18%           
=======================================
  Files         275      275           
  Lines       18958    18958           
  Branches     1773     1773           
=======================================
  Hits        14253    14253           
  Misses       4661     4661           
  Partials       44       44           

Flag	Coverage Δ
backend	99.67% <ø> (ø)
frontend	66.32% <ø> (ø)
sharedComponents	66.84% <ø> (ø)

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