feat: add short-form video section to social-content skill (#257)

Add TikTok/Reels/Shorts frameworks: 3-second rule, video structures,
caption best practices, content ideas by business type. Detailed hook
library, scripting template, audio/visual strategy in reference file.

Inspired by #200 (vendor-neutral parts only).

Co-authored-by: Claude Opus 4.6 <noreply@anthropic.com>

skills/social-content/SKILL.md

@@ -1,8 +1,8 @@
 ---
 name: social-content
-description: "When the user wants help creating, scheduling, or optimizing social media content for LinkedIn, Twitter/X, Instagram, TikTok, Facebook, or other platforms. Also use when the user mentions 'LinkedIn post,' 'Twitter thread,' 'social media,' 'content calendar,' 'social scheduling,' 'engagement,' 'viral content,' 'what should I post,' 'repurpose this content,' 'tweet ideas,' 'LinkedIn carousel,' 'social media strategy,' or 'grow my following.' Use this for any social media content creation, repurposing, or scheduling task. For broader content strategy, see content-strategy."
+description: "When the user wants help creating, scheduling, or optimizing social media content for LinkedIn, Twitter/X, Instagram, TikTok, Facebook, or other platforms. Also use when the user mentions 'LinkedIn post,' 'Twitter thread,' 'social media,' 'content calendar,' 'social scheduling,' 'engagement,' 'viral content,' 'what should I post,' 'repurpose this content,' 'tweet ideas,' 'LinkedIn carousel,' 'social media strategy,' 'grow my following,' 'TikTok video,' 'Reels,' 'Shorts,' 'video script,' 'video hook,' 'short-form video,' or 'create a reel.' Use this for social media content creation, repurposing, scheduling, and short-form video scripting. For broader content strategy, see content-strategy. For paid video ads, see ad-creative."
 metadata:
-  version: 1.2.0
+  version: 1.3.0
 ---
 
 # Social Content
@@ -309,6 +309,87 @@ Instead of guessing, analyze what's working for top creators in your niche:
 
 ---
 
+## Short-Form Video (TikTok, Reels, Shorts)
+
+Short-form video is the highest-reach format on every major platform. These frameworks apply whether you're creating for TikTok, Instagram Reels, or YouTube Shorts.
+
+### Platform Specs
+
+| Platform | Optimal Length | Aspect Ratio | Key Difference |
+|----------|---------------|--------------|----------------|
+| TikTok | 15-60 sec | 9:16 | Trending sounds, raw/authentic feel |
+| Reels | 15-30 sec | 9:16 | Polished content, rewards saves/shares |
+| Shorts | 30-60 sec | 9:16 | YouTube SEO applies, searchable titles |
+
+### The 3-Second Rule
+
+You have 3 seconds to stop the scroll. Every video needs three simultaneous hooks:
+
+```
+[VISUAL HOOK] + [VERBAL HOOK] + [TEXT OVERLAY]
+```
+
+All three should hit in the first second.
+
+### Video Structures
+
+**Problem-Solution (15-30 sec):**
+```
+[0-3s]  Hook: State the problem
+[3-10s] Agitate: Why it matters
+[10-25s] Solution: Your method/product/tip
+[25-30s] CTA: What to do next
+```
+
+**List Format (30-60 sec):**
+```
+[0-3s]  Hook: "X things that [outcome]"
+[3-50s] Items: One every 5-8 seconds
+[50-60s] CTA
+```
+
+**Tutorial (30-60 sec):**
+```
+[0-3s]  Hook: Show the end result first
+[3-8s]  Overview: "Here's how..."
+[8-50s] Steps: Quick, clear instructions
+[50-60s] Result + CTA
+```
+
+### Caption & Subtitle Best Practices
+
+Captions increase watch time by 25-40%. Most social video is watched without sound.
+
+- **MAX 2 lines** on screen at once
+- **3-5 words per line**
+- Bold, sans-serif font with black outline
+- **Highlight key words** in a different color
+- Match timing to speech exactly
+
+Tools: CapCut (free), Descript, Captions.ai, Premiere Pro
+
+### Content Ideas by Type
+
+| Business Type | Video Ideas |
+|---------------|-------------|
+| SaaS | Feature demos (show outcome first), before/after, "Watch me do X in Y seconds" |
+| E-commerce | Unboxing, comparisons, how it's made, customer reviews |
+| Services | Process reveals, client transformations, myth-busting |
+| Personal brand | Lessons learned, controversial takes, day-in-the-life |
+
+### Common Mistakes
+
+1. **Slow hooks** — don't build up to the point
+2. **No text overlay** — many watch without sound
+3. **Poor audio** — bad audio kills retention instantly
+4. **Too long** — if it can be shorter, make it shorter
+5. **No CTA** — tell viewers what to do
+6. **Ignoring comments** — engagement in first hour matters
+
+**For video hook formulas and scripting templates**: See [references/short-form-video.md](references/short-form-video.md)
+
+---
+
 ## Task-Specific Questions
 
 1. What platform(s) are you focusing on?