update diff, think report

[melonattacker]

This pull request updates the documentation to improve clarity, modernize report formats, and introduce new usage examples for the threat-thinker tool. The most important changes are grouped below:

Command and Output Format Improvements:

• Updated all example commands in README.md and docs/tutorials.md to support dual output formats (Markdown and JSON) by using --format both, --out-md, and --out-json flags, making it easier to consume results in different contexts. [1] [2] [3] [4]
• Added links to example Markdown and JSON reports for both web and AWS scenarios to aid user navigation and understanding. [1] [2]

Threat Report Table and Summary Refinement:

• Simplified and clarified the threat tables in the tutorials, focusing on key fields (ID, Threat, Severity, Score) and updating threat descriptions for better readability. [1] [2]
• Enhanced the summary sections to more clearly explain the discovered threats and their implications, with improved wording and organization. [1] [2]

New Feature: Threat Report Diff Analysis:

• Added documentation and usage examples for the new threat-thinker diff command, which allows users to compare threat analysis results between two system architectures and generate change analysis reports in both Markdown and JSON formats. [1] [2]
• Provided a detailed tutorial and summary for diff analysis, including architectural improvements, new risks, and actionable recommendations for evolving systems.

Expanded Tutorials and Recommendations:

• Introduced a new tutorial section for analyzing architectural changes, including diagrams, command usage, and comprehensive findings to help users understand the impact of system evolution on security posture.

These changes collectively make the documentation more user-friendly, highlight new capabilities, and provide actionable guidance for threat analysis workflows.