chore(deps): upgrade major dependencies (ESLint 10, recharts 3, TS 6, Vite 8) (#130)

* chore(deps): upgrade ESLint 9 → 10 with plugin compatibility fixes

- eslint: ^9 → ^10.0.0 (backend + frontend)
- @eslint/js: ^9 → ^10.0.0 (backend + frontend)
- eslint-plugin-react-refresh: ^0.4.24 → ^0.5.2 (ESM, config factory API)
- Update frontend eslint.config.js: destructured import for react-refresh,
  call configs.vite() as factory function (0.5 API change)
- Downgrade new ESLint 10 rules (no-useless-assignment, preserve-caught-error)
  to warnings for existing code patterns
- eslint-plugin-react-hooks stays at 7.0.1 (stable) with --legacy-peer-deps
  until a stable release adds ESLint 10 peer support

* chore(deps): upgrade recharts 2.x to 3.8 with chart.tsx type fixes

recharts 3.x moved Tooltip/Legend props to context-based API.
Updated chart.tsx to use explicit prop interfaces with internal
recharts type imports (LegendPayload, TooltipPayload, TooltipFormatter).

* chore(deps): upgrade TypeScript 5.9 to 6.0

- Remove deprecated baseUrl from frontend tsconfig (paths works standalone in TS 6)
- Add react-is dependency required by recharts 3.x at build time
- Backend and frontend both compile and lint cleanly

* chore(deps): upgrade Vite 7.3 to 8.0 and @vitejs/plugin-react to 6.0

Vite 8 replaces Rollup+esbuild with Rolldown, significantly improving
build speed (~2s vs ~18s). No config changes required.

* fix(ci): add .npmrc with legacy-peer-deps for CI and Docker builds

typescript-eslint@8.x requires typescript <6.0.0 and
eslint-plugin-react-hooks@7.0.1 requires eslint <=9. Until upstream
packages release compatible versions, legacy-peer-deps is needed.

* docs: add logo assets and re-ignore CLAUDE.md

* fix(ci): copy .npmrc into prod-deps Docker stage

The prod-deps stage also runs npm ci with backend/package.json but was
missing the .npmrc needed to bypass peer dep conflicts.

backend/.npmrc

@@ -0,0 +1 @@
+legacy-peer-deps=true

backend/eslint.config.mjs

@@ -22,6 +22,9 @@ export default tseslint.config(
       // Terminal output processing intentionally uses control characters in regexes
       'no-control-regex': 'off',
       'no-console': 'off',
+      // New in ESLint 10 recommended — existing patterns, suppress until addressed
+      'no-useless-assignment': 'warn',
+      'preserve-caught-error': 'warn',
     },
   },
 )

backend/package.json

@@ -15,6 +15,7 @@
   "license": "ISC",
   "type": "commonjs",
   "devDependencies": {
+    "@eslint/js": "^10.0.1",
     "@types/bcrypt": "^6.0.0",
     "@types/better-sqlite3": "^7.6.13",
     "@types/cookie-parser": "^1.4.10",
@@ -23,14 +24,13 @@
     "@types/node": "^25.3.0",
     "@types/supertest": "^7.2.0",
     "@types/yaml": "^1.9.6",
+    "eslint": "^10.1.0",
     "nodemon": "^3.1.13",
     "supertest": "^7.2.2",
     "ts-node": "^10.9.2",
-    "typescript": "^5.9.3",
-    "vitest": "^4.1.0",
-    "@eslint/js": "^9.0.0",
-    "eslint": "^9.0.0",
-    "typescript-eslint": "^8.0.0"
+    "typescript": "^6.0.2",
+    "typescript-eslint": "^8.0.0",
+    "vitest": "^4.1.0"
   },
   "dependencies": {
     "@types/cors": "^2.8.19",