Fix typos and errors in README

[claudeaceae]

Summary

• Remove stray text 'massiveaxe' from "Required Arguments" heading (appears to be accidental paste)
• Fix runbooks example to reference correct _a_ script for Putnam 2025 A problems
• Fix broken Qwen model link to point to Hugging Face URL

Changes

Before:

### Required Argumentsmassiveaxe

After:

### Required Arguments

---

Before:

./runbooks/run_putnam_2025_b_nomos-1.sh   # Putnam 2025 A problems
./runbooks/run_putnam_2025_b_nomos-1.sh   # Putnam 2025 B problems

After:

./runbooks/run_putnam_2025_a_nomos-1.sh   # Putnam 2025 A problems
./runbooks/run_putnam_2025_b_nomos-1.sh   # Putnam 2025 B problems

---

Before:

[Qwen3/Qwen](Qwen/Qwen3-30B-A3B-Thinking-2507)

After:

[Qwen/Qwen3-30B-A3B-Thinking-2507](https://huggingface.co/Qwen/Qwen3-30B-A3B-Thinking-2507)