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/web-design-guidelines/SKILL.md

@@ -0,0 +1,39 @@
+---
+name: web-design-guidelines
+description: Review UI code for Web Interface Guidelines compliance. Use when asked to "review my UI", "check accessibility", "audit design", "review UX", or "check my site against best practices".
+metadata:
+  author: vercel
+  version: "1.0.0"
+  argument-hint: <file-or-pattern>
+---
+
+# Web Interface Guidelines
+
+Review files for compliance with Web Interface Guidelines.
+
+## How It Works
+
+1. Fetch the latest guidelines from the source URL below
+2. Read the specified files (or prompt user for files/pattern)
+3. Check against all rules in the fetched guidelines
+4. Output findings in the terse `file:line` format
+
+## Guidelines Source
+
+Fetch fresh guidelines before each review:
+
+```
+https://raw.githubusercontent.com/vercel-labs/web-interface-guidelines/main/command.md
+```
+
+Use WebFetch to retrieve the latest rules. The fetched content contains all the rules and output format instructions.
+
+## Usage
+
+When a user provides a file or pattern argument:
+1. Fetch guidelines from the source URL above
+2. Read the specified files
+3. Apply all rules from the fetched guidelines
+4. Output findings using the format specified in the guidelines
+
+If no files specified, ask the user which files to review.