fix: add API error handler helper + JSON body size limit (closes #7, closes #9)

[hermesxclaw-ctrl]

Changes

#7 — API Error Handling Helper

• Added apiError() helper for consistent JSON error responses
• Applied try/catch + apiError to both GET and POST /users routes
• Returns proper error shape: { error: true, message: string }

#9 — JSON Body Size Limit

• Added express.json({ limit: MAX_BODY_SIZE }) — defaults to 1mb
• Configurable via MAX_BODY_SIZE env var
• Prevents resource exhaustion from oversized payloads

Files Changed

• apps/api/src/index.ts — body size limit
• apps/api/src/routes/users.ts — error handler helper + try/catch