fix: centralize lint:changed configuration in nx.json (#16877)

## Summary

The `lint:changed` command was not using the correct ESLint config for
`twenty-server`, causing it to use the root `eslint.config.mjs` instead
of the package-specific one. This PR fixes the issue and renames the
command to `lint:diff-with-main` for clarity.

## Problem

- `twenty-front` correctly specified `--config
packages/twenty-front/eslint.config.mjs`
- `twenty-server` just called `npx eslint` without specifying a config
- This meant `twenty-server` was missing important rules like:
  - `@typescript-eslint/no-explicit-any: 'error'`
  - `@stylistic/*` rules (linebreak-style, padding, etc.)
  - `import/order` with NestJS patterns
- Custom workspace rules (`@nx/workspace-inject-workspace-repository`,
etc.)

## Solution

1. **Renamed** `lint:changed` to `lint:diff-with-main` to be explicit
about what the command does
2. **Centralized** the configuration in `nx.json` targetDefaults:
- Uses `{projectRoot}` interpolation for paths (resolved by Nx at
runtime)
   - Each package automatically uses its own ESLint config
- Packages can override specific options (e.g., file extension pattern)
3. **Simplified** `project.json` files by inheriting from defaults

## Usage

```bash
# Lint only files changed vs main branch
npx nx lint:diff-with-main twenty-front
npx nx lint:diff-with-main twenty-server

# Auto-fix files changed vs main
npx nx lint:diff-with-main twenty-front --configuration=fix
```

## Changes

- **nx.json**: Added `lint:diff-with-main` target default with
configurable pattern
- **twenty-front/project.json**: Simplified to inherit from defaults
- **twenty-server/project.json**: Overrides pattern to include `.json`
files
- **CLAUDE.md** and **.cursor/rules**: Updated documentation

CLAUDE.md

@@ -36,11 +36,10 @@ When testing the UI end to end, click on "Continue with Email" and use the prefi
 
 ### Code Quality
 ```bash
-# Linting (changed files only - fastest)
-npx nx lint:changed twenty-front           # Lint only changed files vs main
-npx nx lint:changed twenty-server          # Lint only changed files vs main
-npx nx lint:changed twenty-front --configuration=fix  # Auto-fix changed files
-npx nx lint:changed twenty-front --configuration=staged  # Lint staged files only
+# Linting (diff with main - fastest)
+npx nx lint:diff-with-main twenty-front           # Lint only files changed vs main
+npx nx lint:diff-with-main twenty-server          # Lint only files changed vs main
+npx nx lint:diff-with-main twenty-front --configuration=fix  # Auto-fix files changed vs main
 
 # Linting (full project)
 npx nx lint twenty-front      # Lint all files in frontend