Adds the missing create_project tool definition and executor to
assistant-tools.ts, enabling the AI chatbot to create new projects
when provided with the required information (shortCode, name,
orderType, budgetCents, startDate, endDate).
Includes validation for enums, short code format/uniqueness, date
range, and optional blueprint/client lookup by name. Follows the
same permission guard pattern as existing write tools.
Closes#14
Co-Authored-By: claude-flow <ruv@ruv.net>