fix: comprehensive TypeScript/build fixes and modernization

- Update tsconfig to ES2024 target and bundler moduleResolution
- Add dynamic imports for chart.js and recharts (bundle optimization)
- Consolidate 17 useState into useReducer in sessions page
- Fix 18 .js extension imports across lib files
- Add type declarations for @rapideditor/country-coder
- Fix platform user types (PlatformUserRole enum)
- Fix Calendar component prop types
- Centralize next-auth type augmentation
- Add force-dynamic to all API routes (prevent build-time prerender)
- Fix Prisma JSON null handling with Prisma.DbNull
- Fix various type mismatches (SessionMessage, ImportRecord, etc.)
- Export ButtonProps from button component
- Update next-themes import path
- Replace JSX.Element with React.ReactElement
- Remove obsolete debug scripts and pnpm lockfile
- Downgrade eslint to v8 for next compatibility

.github/skills/vercel-react-best-practices/rules/js-length-check-first.md

@@ -0,0 +1,49 @@
+---
+title: Early Length Check for Array Comparisons
+impact: MEDIUM-HIGH
+impactDescription: avoids expensive operations when lengths differ
+tags: javascript, arrays, performance, optimization, comparison
+---
+
+## Early Length Check for Array Comparisons
+
+When comparing arrays with expensive operations (sorting, deep equality, serialization), check lengths first. If lengths differ, the arrays cannot be equal.
+
+In real-world applications, this optimization is especially valuable when the comparison runs in hot paths (event handlers, render loops).
+
+**Incorrect (always runs expensive comparison):**
+
+```typescript
+function hasChanges(current: string[], original: string[]) {
+  // Always sorts and joins, even when lengths differ
+  return current.sort().join() !== original.sort().join()
+}
+```
+
+Two O(n log n) sorts run even when `current.length` is 5 and `original.length` is 100. There is also overhead of joining the arrays and comparing the strings.
+
+**Correct (O(1) length check first):**
+
+```typescript
+function hasChanges(current: string[], original: string[]) {
+  // Early return if lengths differ
+  if (current.length !== original.length) {
+    return true
+  }
+  // Only sort when lengths match
+  const currentSorted = current.toSorted()
+  const originalSorted = original.toSorted()
+  for (let i = 0; i < currentSorted.length; i++) {
+    if (currentSorted[i] !== originalSorted[i]) {
+      return true
+    }
+  }
+  return false
+}
+```
+
+This new approach is more efficient because:
+- It avoids the overhead of sorting and joining the arrays when lengths differ
+- It avoids consuming memory for the joined strings (especially important for large arrays)
+- It avoids mutating the original arrays
+- It returns early when a difference is found