chore: upgrade toolchain majors (TypeScript 6, Vite 8, svgr 5, tsconfig-paths 6)

[devin-ai-integration]

Summary

Build-toolchain-only major upgrades; no runtime/MUI deps touched:

• typescript 5.9 → 6.0.3, vite 7 → 8.0.16, vite-plugin-svgr 4 → 5.2.0, vite-tsconfig-paths 5 → 6.1.1
• @vitejs/plugin-react-swc, @tailwindcss/vite/tailwindcss bumped to latest minors for Vite 8 compatibility
• tsconfig target/lib ES2020 → ES2022

Two fallout fixes required:

• TS 6 introduces TS2882 (side-effect imports must resolve to type declarations), so added src/css.d.ts with declare module "*.css" to cover CSS imports like import "./css/planner.css".
• Vite 8 minifies CSS with LightningCSS, which hard-errors on flatpickr's legacy IE hack (@media (min-width:0\0)). Set css.lightningcss.errorRecovery: true in vite.config.ts so the invalid query is stripped (warning only) instead of failing the build.

Validated: npm run verify (oxlint + prettier + tsc + vite build) and npx react-doctor@latest -y --offline --fail-on error (100/100) pass.

Link to Devin session: https://app.devin.ai/sessions/2eb2f53798ef4b36806b3b68cee6bbd5
Requested by: @rchalamala

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Status	Name	Latest Commit	Preview URL	Updated (UTC)
✅ Deployment successful! View logs	caltech-dev	95088ab	Commit Preview URL Branch Preview URL	Jun 11 2026, 04:18 AM

[devin-ai-integration]

Devin Review found 2 potential issues.

[devin-ai-integration]

🚩 Major version bumps may require migration steps

This PR bumps four dev dependencies across major versions: TypeScript 5→6, Vite 7→8, vite-plugin-svgr 4→5, and vite-tsconfig-paths 5→6. Major version bumps can introduce breaking changes. The new src/css.d.ts (declare module "*.css") and the css.lightningcss.errorRecovery config addition suggest some migration work was already done (Vite 8 uses lightningcss by default and may no longer provide built-in CSS type declarations). It would be worth verifying the build succeeds end-to-end with these versions and that no other migration steps are needed.

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[devin-ai-integration]

📝 Info: css.d.ts added to compensate for Vite 8 dropping CSS type declarations

The addition of declare module "*.css" is needed because newer versions of Vite/vite-plugin-svgr may no longer provide ambient CSS module declarations via vite/client types. This is confirmed by the CSS imports in src/Planner.tsx:11-14 and src/index.tsx:5 which import .css files directly. Without this declaration, TypeScript would error on those imports. This is a correct migration step.

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[devin-ai-integration]

Test results — ran the Vite 8 dev server locally and exercised the app end-to-end in Chrome (Devin session).

• It should serve the app via Vite 8 dev server with intact styling — passed
• It should search and add a course (fzf fuzzy search, 39 results for "cs 1") — passed
• It should render schedule events + styled flatpickr time picker — passed (Ma/CS 106 a at 1 PM MWF+R)
• It should remove/restore calendar events on course toggle — passed (0 units ↔ 9 units)
• npm run verify and npx react-doctor@latest -y --offline --fail-on error (100/100) — passed
• CI: all 6 checks passed

App renders styled (Vite 8)	Schedule events + flatpickr picker

Notes on required migration fixes

• TS 6 new error TS2882 on side-effect CSS imports → added src/css.d.ts (declare module "*.css").
• Vite 8's LightningCSS minifier hard-errors on flatpickr's legacy IE @media (min-width:0\0) hack → css.lightningcss.errorRecovery: true in vite.config.ts (the build logs a stripped-query warning; harmless, IE-only rule).
• tsconfig target/lib ES2020 → ES2022 with no new errors.
• Vite 8 suggests replacing vite-tsconfig-paths with native resolve.tsconfigPaths: true; kept the plugin per requested scope.

[devin-ai-integration]

Devin Review found 2 new potential issues.

[devin-ai-integration]

📝 Info: @vitejs/plugin-react-swc version not bumped but compatible

The @vitejs/plugin-react-swc remains at ^4.3.1 while Vite was bumped to 8.x. Per the lockfile, version 4.3.1 declares peerDependencies: { "vite": "^4 || ^5 || ^6 || ^7 || ^8" }, so this is compatible. No version bump needed here.

(Refers to line 45)

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[devin-ai-integration]

📝 Info: Vite 8 LightningCSS errorRecovery for flatpickr compatibility

Vite 8 uses LightningCSS as the default CSS processor (replacing PostCSS). The errorRecovery: true option is correctly added to handle flatpickr's legacy IE CSS hacks (@media (min-width:0\0)). Without this, the build would fail on flatpickr's CSS. This is a valid workaround, though longer-term the project could consider replacing flatpickr (which is unmaintained) with a modern date picker that doesn't require legacy CSS hacks.

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