Add mathematical proof techniques documentation including Jordan normal form

[Copilot]

Issue "Jordan form of a proof" with instruction "A discrete option" interpreted as request for mathematical proof documentation in discrete mathematics context.

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Changes

New appendix section 16.4 covering proof techniques used in algorithm analysis:

Core Content

• Direct proof, contradiction, induction, constructive proof with examples
• Algorithm correctness proofs (greedy choice property, dynamic programming)
• Jordan normal form as advanced topic with applications to graph adjacency matrices and Markov chains

Files Added

• docs/chapter_appendix/proof_techniques.md (中文)
• en/docs/chapter_appendix/proof_techniques.md (English)
• zh-hant/docs/chapter_appendix/proof_techniques.md (繁體中文)
• ja/docs/chapter_appendix/proof_techniques.md (日本語)

Navigation

Updated all four mkdocs.yml files to include new section in appendix chapter.

Discrete Context Note

Explicitly addresses "discrete option" requirement by positioning Jordan normal form within discrete mathematics applications (graph spectral analysis, Markov chain analysis) rather than continuous mathematics.

Original prompt

---

This section details on the original issue you should resolve

<issue_title>Jordan form of a proof.</issue_title>
<issue_description></issue_description>

<agent_instructions>A discrete option.</agent_instructions>

Comments on the Issue (you are @copilot in this section)

• Fixes Jordan form of a proof. #7

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