Seed content: Number Properties & Exponents (+6 questions, +2 lessons)

[DMDaudio]

What does this PR add or change?

A coherent Quant batch on number properties and exponents that fills several previously uncovered subtopics, plus a Verbal Critical Reasoning paradox question (a new CR subtopic in the bank).

Lessons (2)

• quant-arithmetic-exponents-roots — Exponents and Roots (rules, common-base matching, negative/fractional exponents, the "sums of powers are factored, not combined" trap)
• quant-number-properties-remainders — Remainders (division identity, remainders through +/×, units-digit cyclicity)

Questions (6)

• quant-arithmetic-exponents-roots-0017 (easy) — substitution with 2^(x+3)
• quant-arithmetic-exponents-roots-0018 (medium) — factoring equal powers, 3^n+3^n+3^n=3^7
• quant-number-properties-remainders-0019 (medium) — remainder of 3n given n ≡ 3 (mod 5)
• quant-number-properties-odds-evens-signs-0020 (medium) — parity, n²+n = n(n+1) is always even
• quant-number-properties-factors-multiples-0021 (hard) — divisible by neither 2 nor 3, inclusion–exclusion
• verbal-critical-reasoning-paradox-0009 (medium) — resolve/explain

Rebuilds docs/data/content.json via node scripts/build.mjs (now 38 questions, 10 lessons; build reports zero warnings). No app/schema changes.

Type of change

• New question(s)
• New lesson(s)
• Fix to existing content (answer / explanation / tag)
• Tooling / docs / schema

Author checklist

• This is my own original work — not copied or paraphrased from any real GMAT question or prep material.
• Front-matter follows CONTENT_SCHEMA.md (id matches the filename; topic/subtopic exist in curriculum.md).
• I solved every question myself and confirmed exactly one answer choice is correct.
• Each explanation would help someone who got the question wrong, and names the trap where relevant.
• status is in-review. I did not set my own content to verified.

For reviewers

• I solved the question(s) without reading the keyed answer first and got the same answer.
• Exactly one choice is correct; distractors are plausible.
• Explanation and tags (section / topic / difficulty) are accurate.
• If approving: bumped status to verified and added my handle to reviewers.

🤖 Generated with Claude Code

https://claude.ai/code/session_01UKcsGFztmGMUBUYfPSzfhW

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Generated by Claude Code