2x Faster CLI Startup & Smarter Project Detection

CLI startup speed improved by 2x, smarter project root detection with boundary markers for monorepos, and reasoning effort validation for OpenAI models.

#1523 fc1a79f Thanks @Crunchyman-ralph! - Codex cli Validate reasoning effort against model capabilities
- Add provider-level reasoning effort validation for OpenAI models
- Automatically cap unsupported effort levels (e.g., 'xhigh' on gpt-5.1 and gpt-5 becomes 'high')
#1549 98087ac Thanks @Crunchyman-ralph! - Improve CLI startup speed by 2x
#1545 a0007a3 Thanks @Crunchyman-ralph! - Smarter project root detection with boundary markers
- Prevents Task Master from incorrectly detecting .taskmaster folders in your home directory when working inside a different project
- Now stops at project boundaries (.git, package.json, lock files) instead of searching all the way up to the filesystem root
- Adds support for monorepo markers (lerna.json, nx.json, turbo.json) and additional lock files (bun.lockb, deno.lock)
#1523 fc1a79f Thanks @Crunchyman-ralph! - Improve json schemas for ai-related commands making it more compatible with openai models
#1542 b817d6f Thanks @mdimitrovg! - Fixed vertex-ai authentication when using service account and vertex location env variable.