fix(skills): remove phantom resource references and fix CoC links (#447)

Remove references to non-existent resource files (references/, assets/,
scripts/, examples/) from 115 skill SKILL.md files. These sections
pointed to directories and files that were never created, causing
confusion when users install skills.

Also fix broken Code of Conduct links in issue templates to use
absolute GitHub URLs instead of relative paths that 404.

plugins/startup-business-analyst/skills/market-sizing-analysis/SKILL.md

@@ -414,25 +414,6 @@ TAM = Total Target Companies × Average Deal Size × Deals per Year
 - Consider competitive intensity
 - Factor in switching costs and barriers
 
-## Additional Resources
-
-### Reference Files
-
-For detailed methodologies and frameworks:
-
-- **`references/methodology-deep-dive.md`** - Comprehensive guide to each methodology with step-by-step worksheets
-- **`references/data-sources.md`** - Curated list of market research sources, databases, and tools
-- **`references/industry-templates.md`** - Specific templates for SaaS, marketplace, consumer, B2B, and fintech markets
-
-### Example Files
-
-Working examples with complete calculations:
-
-- **`examples/saas-market-sizing.md`** - Complete TAM/SAM/SOM for a B2B SaaS product
-- **`examples/marketplace-sizing.md`** - Marketplace platform market opportunity calculation
-- **`examples/value-theory-example.md`** - Value-based market sizing for disruptive innovation
-
-Use these examples as templates for your own market sizing analysis. Each includes real numbers, data sources, and assumptions documented clearly.
 
 ## Quick Start
 
@@ -447,5 +428,3 @@ To perform market sizing analysis:
 7. **Validate** - Cross-check with alternative methods
 8. **Document** - Show methodology, sources, assumptions
 9. **Present** - Structure for audience (investors, strategy, operations)
-
-For detailed step-by-step guidance on each methodology, reference the files in `references/` directory. For complete worked examples, see `examples/` directory.