feat: rename 15 skills for shorter, cleaner names

Renames:
- ab-test-setup → ab-testing
- analytics-tracking → analytics
- competitor-alternatives → competitors
- email-sequence → emails
- free-tool-strategy → free-tools
- launch-strategy → launch
- onboarding-cro → onboarding
- paywall-upgrade-cro → paywalls
- popup-cro → popups
- pricing-strategy → pricing
- product-marketing-context → product-marketing
- referral-program → referrals
- schema-markup → schema
- signup-flow-cro → signup
- social-content → social

Updates all cross-references in skills, references, tools,
marketplace.json, README, AGENTS.md, and CONTRIBUTING.md.

BREAKING: Users with installed skills will need to reinstall.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

skills/free-tools/references/tool-types.md

@@ -0,0 +1,217 @@
+# Free Tool Types Reference
+
+Detailed guide to each type of marketing tool you can build.
+
+## Contents
+- Calculators
+- Generators
+- Analyzers/Auditors
+- Testers/Validators
+- Libraries/Resources
+- Interactive Educational
+- Tool Concept Examples by Industry (SaaS product, agency/services, e-commerce, developer tools, finance)
+
+## Calculators
+
+**Best for**: Decisions involving numbers, comparisons, estimates
+
+**Examples**:
+- ROI calculator
+- Savings calculator
+- Cost comparison tool
+- Salary calculator
+- Tax estimator
+- Pricing estimator
+- Compound interest calculator
+- Break-even calculator
+
+**Why they work**:
+- Personalized output
+- High perceived value
+- Share-worthy results
+- Clear problem → solution
+
+**Implementation tips**:
+- Keep inputs simple
+- Show calculations transparently
+- Make results shareable
+- Add "powered by" branding
+
+---
+
+## Generators
+
+**Best for**: Creating something useful quickly
+
+**Examples**:
+- Policy generator (privacy, terms)
+- Template generator
+- Name/tagline generator
+- Email subject line generator
+- Resume builder
+- Color palette generator
+- Logo maker
+- Contract generator
+
+**Why they work**:
+- Tangible output
+- Saves time
+- Easily shared
+- Repeat usage
+
+**Implementation tips**:
+- Output should be immediately usable
+- Allow customization
+- Offer download/export options
+- Include email gating for premium outputs
+
+---
+
+## Analyzers/Auditors
+
+**Best for**: Evaluating existing work or assets
+
+**Examples**:
+- Website grader
+- SEO analyzer
+- Email subject tester
+- Headline analyzer
+- Security checker
+- Performance auditor
+- Accessibility checker
+- Code quality analyzer
+
+**Why they work**:
+- Curiosity-driven
+- Personalized insights
+- Creates awareness of problems
+- Natural lead to solution
+
+**Implementation tips**:
+- Score or grade for gamification
+- Benchmark against averages
+- Provide actionable recommendations
+- Follow up with improvement offers
+
+---
+
+## Testers/Validators
+
+**Best for**: Checking if something works
+
+**Examples**:
+- Meta tag preview
+- Email rendering test
+- Mobile-friendly test
+- Speed test
+- DNS checker
+- SSL certificate checker
+- Redirect checker
+- Broken link finder
+
+**Why they work**:
+- Immediate utility
+- Bookmark-worthy
+- Repeat usage
+- Professional necessity
+
+**Implementation tips**:
+- Fast results are essential
+- Show pass/fail clearly
+- Provide fix instructions
+- Integrate with your product where relevant
+
+---
+
+## Libraries/Resources
+
+**Best for**: Reference material
+
+**Examples**:
+- Icon library
+- Template library
+- Code snippet library
+- Example gallery
+- Industry directory
+- Resource list
+- Swipe file collection
+- Font pairing tool
+
+**Why they work**:
+- High SEO value
+- Ongoing traffic
+- Establishes authority
+- Linkable asset
+
+**Implementation tips**:
+- Make searchable/filterable
+- Allow easy copying/downloading
+- Update regularly
+- Accept community submissions
+
+---
+
+## Interactive Educational
+
+**Best for**: Learning/understanding
+
+**Examples**:
+- Interactive tutorials
+- Code playgrounds
+- Visual explainers
+- Quizzes/assessments
+- Simulators
+- Comparison tools
+- Decision trees
+- Configurators
+
+**Why they work**:
+- Engages deeply
+- Demonstrates expertise
+- Shareable
+- Memory-creating
+
+**Implementation tips**:
+- Make it hands-on
+- Show immediate feedback
+- Lead to deeper resources
+- Capture engaged users
+
+---
+
+## Tool Concept Examples by Industry
+
+### SaaS Product
+- Product ROI calculator
+- Competitor comparison tool
+- Readiness assessment quiz
+- Template library for use case
+- Feature configurator
+
+### Agency/Services
+- Industry benchmark tool
+- Project scoping calculator
+- Portfolio review tool
+- Cost estimator
+- Proposal generator
+
+### E-commerce
+- Product finder quiz
+- Comparison tool
+- Size/fit calculator
+- Savings calculator
+- Gift finder
+
+### Developer Tools
+- Code snippet library
+- Testing/preview tool
+- Documentation generator
+- Interactive tutorials
+- API playground
+
+### Finance
+- Financial calculators
+- Investment comparison
+- Budget planner
+- Tax estimator
+- Loan calculator