fix: add CAMOFOX_MAX_BODY_SIZE env var to control body parser limit

[igitur]

Problem

The /tabs/:tabId/evaluate endpoint has a 1MB body limit override, but it's dead code — the global express.json({ limit: '100kb' }) middleware on line 120 runs first and rejects any body larger than 100KB before the evaluate-specific parser ever fires.

This makes it impossible to pass large expressions to evaluate, which is important for:

• Injecting base64-encoded binary data (e.g., file uploads via FormData + fetch)
• Passing large JSON payloads through evaluate

Fix

Add CAMOFOX_MAX_BODY_SIZE env var (default: '100kb') to lib/config.js — the centralized config module where all other env vars live. Then use CONFIG.maxBodySize in both places:

• lib/config.js: maxBodySize: process.env.CAMOFOX_MAX_BODY_SIZE || '100kb'
• Global parser: express.json({ limit: CONFIG.maxBodySize })
• Evaluate parser: express.json({ limit: CONFIG.maxBodySize })

The cookies endpoint (512kb) and extract endpoint (256kb) are intentionally unchanged — they have their own specific limits.

Usage

# Default (100KB, backward compatible)
camofox-browser

# Increase to 10MB for large evaluate payloads
CAMOFOX_MAX_BODY_SIZE=10mb camofox-browser

Closes #8397

[skyfallsin]

Thanks @igitur — merged, with your original commit retained in the history.

The follow-up keeps the global JSON limit at 100kb and applies the configurable CAMOFOX_EVALUATE_MAX_BODY_SIZE limit only to POST /tabs/:tabId/evaluate, so the cookie and extract limits are not widened. It also forwards the setting to plugin-launched server subprocesses, documents it, and adds config and E2E coverage.