Add design for issue 24 and README example fix

- PDF manual download via GitHub Pages
- Fix README Quick Start to use correct imports and show ILP reduction

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

Author: GiggleLiu

docs/plans/2026-02-06-issue24-pdf-readme-design.md

@@ -0,0 +1,80 @@
+# Design: Issue 24 - PDF Download & README Example Fix
+
+## Overview
+
+This design addresses two related improvements:
+1. **Issue 24**: Add PDF manual download to documentation
+2. **README fix**: Update Quick Start example to use correct imports and show ILP reduction
+
+## Part 1: README Example Fix
+
+### Problem
+The current README example uses `IndependentSetT` and `VertexCoverT` which are not exported in `prelude::*`, causing compilation errors.
+
+### Solution
+Replace with `IndependentSet` (which IS in prelude) and demonstrate the more valuable ILP reduction workflow.
+
+### Updated Example
+
+```rust
+use problemreductions::prelude::*;
+use problemreductions::models::optimization::ILP;
+
+// Create an Independent Set problem on a path graph
+let problem = IndependentSet::<i32>::new(4, vec![(0, 1), (1, 2), (2, 3)]);
+
+// Reduce to Integer Linear Programming
+let reduction = ReduceTo::<ILP>::reduce_to(&problem);
+let ilp = reduction.target_problem();
+
+// Solve with ILP solver (efficient for larger instances)
+let solver = ILPSolver::new();
+let ilp_solution = solver.solve(ilp).unwrap();
+
+// Extract solution back to original problem
+let solution = reduction.extract_solution(&ilp_solution);
+assert_eq!(solution.iter().sum::<usize>(), 2); // Max IS size is 2
+```
+
+This demonstrates the core value proposition: reduce NP-hard problems to ILP for efficient solving.
+
+## Part 2: Issue 24 - PDF Download
+
+### Requirements
+- Compile typst paper to PDF in CI
+- Host PDF on GitHub Pages
+- Add prominent badge in README
+
+### README Badge
+
+Add after existing badges:
+```markdown
+[![PDF Manual](https://img.shields.io/badge/PDF-Manual-blue)](https://codingthrust.github.io/problem-reductions/reductions.pdf)
+```
+
+### Workflow Changes (docs.yml)
+
+Add to build job:
+
+```yaml
+- name: Install Typst
+  run: |
+    curl -sSL https://github.com/typst/typst/releases/download/v0.12.0/typst-x86_64-unknown-linux-musl.tar.xz | tar -xJ
+    mv typst-x86_64-unknown-linux-musl/typst "$HOME/bin/"
+
+- name: Build PDF
+  run: typst compile docs/paper/reductions.typ book/reductions.pdf
+```
+
+## Implementation Checklist
+
+- [ ] Update README.md Quick Start example
+- [ ] Add PDF badge to README.md
+- [ ] Add typst installation step to docs.yml
+- [ ] Add PDF compilation step to docs.yml
+- [ ] Test workflow locally if possible
+
+## Files to Modify
+
+1. `README.md` - Fix example, add badge
+2. `.github/workflows/docs.yml` - Add typst compilation