Fixed many typos, mistakes, and misleading content

[DanielHashmi]

🔧 Fix Documentation and Code Issues in AI Agents Tutorial

This pull request addresses critical documentation errors and code inconsistencies in the 01_ai_agents_first directory that were causing confusion for students.

What's Fixed

Documentation Corrections:

• Agent Lifecycle Clarity: Fixed misleading statements about LLM calls occurring "multiple times" during single agent turn
• Expected Outcomes: Updated unrealistic expected outputs to match actual system behavior (e.g., user deletion responses)
• Hook Descriptions: Corrected inaccurate explanations of when and how agent lifecycle hooks are triggered

Code Fixes:

• Import Statements: Standardized module imports from openai_agents to agents across all examples
• Syntax Errors: Fixed missing commas, incorrect function parameters, and malformed agent initialization
• Tool Configuration: Corrected failure_error_function parameter usage in function decorators

Impact

• Reduces Student Confusion: Eliminates contradictory information about agent behavior
• Improves Code Reliability: All code examples now run without syntax errors
• Enhances Learning Experience: Students can focus on concepts rather than debugging documentation mistakes

Files Changed

• 01_ai_agents_first/15_advanced_tools/README.md
• 01_ai_agents_first/15_advanced_tools/tools_masterclass/part4.py
• 01_ai_agents_first/19_agent_lifecycle/README.md
• 01_ai_agents_first/20_run_lifecycle/README.md
• 01_ai_agents_first/28_context_engineering/readme.md
• 01_ai_agents_first/projects/Agentic-rag/basic/agent/agent_with_custom_session.py