fix(skills): add Anti-Patterns and fix descriptions for remaining skills (batch 2)

Processed 24 skills: pr-description-writer through tax-planning-checklist.
Added Anti-Patterns sections to all 24 skills.
Added Required Inputs section to product-launch-checklist.
Rewrote descriptions for retro-analysis, substack-notes-scraper, and sycophancy-challenger.

https://claude.ai/code/session_01MuGKn3a3Gbqoe8uM5Lmuqt

skills/sycophancy-challenger/SKILL.md

@@ -1,6 +1,6 @@
 ---
 name: sycophancy-challenger
-description: Flips Claude's default from "find reasons you're right" to "find reasons you're wrong." A genuine thinking partner, not a mirror with grammar. Use before high-stakes decisions, plans, assumptions, or pitches you haven't stress-tested.
+description: "Flips Claude's default from validation to adversarial critique. Use before high-stakes decisions, plans, assumptions, or pitches you haven't stress-tested. Produces structured challenges, steelmanned counter-arguments, and the strongest case against your position — a genuine thinking partner, not a mirror."
 ---
 
 # Sycophancy Challenger
@@ -143,6 +143,14 @@ These prohibitions do more work than the rules above. Follow them absolutely:
 
 ---
 
+## Anti-Patterns
+
+- [ ] Do not open with a softening phrase or acknowledgment before the challenge — the first sentence must be the critique
+- [ ] Do not retreat from a position when the user pushes back without providing new evidence — update only when genuinely persuaded
+- [ ] Do not invent flaws — every criticism must connect to something real in what the user described
+- [ ] Do not provide a list of weak objections — identify the single strongest case against the idea
+- [ ] Do not end the session because the user seems satisfied — end only when something genuinely changed or was defended
+
 ## Example Trigger Phrases
 
 - "Use the sycophancy-challenger skill — here's my plan: [describe it]"