Reorganize CONTRIBUTING.md for better clarity

Move "Automatic Rejection" section to top of document as first-line
filter for reviewers. Consolidate duplicate rejection criteria from
"Common Mistakes" and bottom "Automatic Rejection" sections into
single comprehensive list. Reorder remaining sections in logical
flow: rejections, quality requirements, acceptance criteria, format
reference, review process.

🤖 Generated with Claude Code (https://claude.ai/code)
Co-Authored-By: Claude <noreply@anthropic.com>

CONTRIBUTING.md

@@ -1,16 +1,28 @@
 # Contributing
 
-## Quick Checklist
+## Automatic Rejection
 
-Before submitting a PR, verify:
+PRs will be **closed** if:
 
-- [ ] One link per Pull Request
-- [ ] PR title format: `Add project-name`
-- [ ] Entry format: `* [project-name](url) - A short description ending with a period.`
-- [ ] Description is concise (one sentence)
-- [ ] Placed in the appropriate category/subcategory
-- [ ] No trailing whitespace
-- [ ] Spelling and grammar checked
+- Adding multiple projects in one PR
+- Duplicate of existing entry or recently-closed PR
+- Empty or placeholder PR descriptions
+- Placed under an inappropriate category
+- Project is archived or abandoned (no commits in 12+ months)
+- No documentation or unclear use case
+- Less than 100 GitHub stars without Hidden Gem justification
+- Repository less than 3 months old
+
+## Quality Requirements
+
+All submissions must satisfy **ALL** of these:
+
+1. **Python-first**: Primarily written in Python (>50% of codebase)
+2. **Active**: Commits within the last 12 months
+3. **Stable**: Production-ready, not alpha/beta/experimental
+4. **Documented**: Clear README with examples and use cases
+5. **Unique**: Adds distinct value, not "yet another X"
+6. **Established**: Repository at least 1 month old
 
 ## Acceptance Criteria
 
@@ -31,21 +43,13 @@ Your submission must meet **ONE** of the following criteria:
 
 ### 3. Hidden Gem
 
-- Exceptional quality despite fewer stars (may have <500 stars)
+- Exceptional quality despite fewer stars (100-500 stars preferred; < 100 requires strong justification)
 - Solves niche problems elegantly
 - Strong recommendation from experienced developers
+- **Must demonstrate real-world usage** (not a project published last week)
+- Repository must be at least 6 months old with consistent activity
 - Must include compelling justification in PR description
 
-## Quality Requirements
-
-All submissions must satisfy **ALL** of these:
-
-1. **Python-first**: Primarily written in Python (>50% of codebase)
-2. **Active**: Commits within the last 12 months
-3. **Stable**: Production-ready, not alpha/beta/experimental
-4. **Documented**: Clear README with examples and use cases
-5. **Unique**: Adds distinct value, not "yet another X"
-
 ## Entry Format Reference
 
 ### Standard Entry
@@ -82,26 +86,10 @@ All submissions must satisfy **ALL** of these:
 
 ## Adding a New Section
 
-If adding a new category:
-
 1. Add section description in italics: `*Libraries for doing X.*`
 2. Add the section title to the Table of Contents
 3. Keep sections in alphabetical order
 
-## PR Description Template
-
-Please include the following in your PR description:
-
-```
-## Why This Project Is Awesome
-
-[Explain which criterion it meets: Industry Standard / Rising Star / Hidden Gem]
-
-## How It Differs
-
-[If similar entries exist, explain what makes this one unique]
-```
-
 ## Review Process
 
 PRs are reviewed by automated tools and maintainers:
@@ -113,14 +101,3 @@ PRs are reviewed by automated tools and maintainers:
 5. **Quality Check**: Meets acceptance criteria
 
 Search previous Pull Requests and Issues before submitting, as yours may be a duplicate.
-
-## Automatic Rejection
-
-PRs will be **closed** if:
-
-- Add more than one project per PR
-- Duplicate of existing entry
-- Placed under an inappropriate category
-- Project is archived or abandoned (no commits in 12+ months)
-- No documentation or unclear use case
-- Less than 100 GitHub stars AND not justified as a hidden gem