Optimize skill files for AI agent use with progressive disclosure

- Fix marketplace.json: add 2 missing skills (content-strategy, product-marketing-context)
- Refactor 10 skills over 500 lines to use references/ folders:
  - email-sequence: 926 → 291 lines
  - social-content: 809 → 276 lines
  - competitor-alternatives: 750 → 253 lines
  - pricing-strategy: 712 → 226 lines
  - programmatic-seo: 628 → 235 lines
  - referral-program: 604 → 239 lines
  - schema-markup: 598 → 175 lines
  - free-tool-strategy: 576 → 176 lines
  - paywall-upgrade-cro: 572 → 224 lines
  - marketing-ideas: 566 → 165 lines

Each skill now has core workflow in SKILL.md (<500 lines) with detailed
content in references/ folder for progressive disclosure.

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

skills/social-content/references/platforms.md

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+# Platform-Specific Strategy Guide
+
+Detailed strategies for each major social platform.
+
+## LinkedIn
+
+**Best for:** B2B, thought leadership, professional networking, recruiting
+**Audience:** Professionals, decision-makers, job seekers
+**Posting frequency:** 3-5x per week
+**Best times:** Tuesday-Thursday, 7-8am, 12pm, 5-6pm
+
+**What works:**
+- Personal stories with business lessons
+- Contrarian takes on industry topics
+- Behind-the-scenes of building a company
+- Data and original insights
+- Carousel posts (document format)
+- Polls that spark discussion
+
+**What doesn't:**
+- Overly promotional content
+- Generic motivational quotes
+- Links in the main post (kills reach)
+- Corporate speak without personality
+
+**Format tips:**
+- First line is everything (hook before "see more")
+- Use line breaks for readability
+- 1,200-1,500 characters performs well
+- Put links in comments, not post body
+- Tag people sparingly and genuinely
+
+**Algorithm tips:**
+- First hour engagement matters most
+- Comments > reactions > clicks
+- Dwell time (people reading) signals quality
+- No external links in post body
+- Document posts (carousels) get strong reach
+- Polls drive engagement but don't build authority
+
+---
+
+## Twitter/X
+
+**Best for:** Tech, media, real-time commentary, community building
+**Audience:** Tech-savvy, news-oriented, niche communities
+**Posting frequency:** 3-10x per day (including replies)
+**Best times:** Varies by audience; test and measure
+
+**What works:**
+- Hot takes and opinions
+- Threads that teach something
+- Behind-the-scenes moments
+- Engaging with others' content
+- Memes and humor (if on-brand)
+- Real-time commentary on events
+
+**What doesn't:**
+- Pure self-promotion
+- Threads without a strong hook
+- Ignoring replies and mentions
+- Scheduling everything (no real-time presence)
+
+**Format tips:**
+- Tweets under 100 characters get more engagement
+- Threads: Hook in tweet 1, promise value, deliver
+- Quote tweets with added insight beat plain retweets
+- Use visuals to stop the scroll
+
+**Algorithm tips:**
+- Replies and quote tweets build authority
+- Threads keep people on platform (rewarded)
+- Images and video get more reach
+- Engagement in first 30 min matters
+- Twitter Blue/Premium may boost reach
+
+---
+
+## Instagram
+
+**Best for:** Visual brands, lifestyle, e-commerce, younger demographics
+**Audience:** 18-44, visual-first consumers
+**Posting frequency:** 1-2 feed posts per day, 3-10 Stories per day
+**Best times:** 11am-1pm, 7-9pm
+
+**What works:**
+- High-quality visuals
+- Behind-the-scenes Stories
+- Reels (short-form video)
+- Carousels with value
+- User-generated content
+- Interactive Stories (polls, questions)
+
+**What doesn't:**
+- Low-quality images
+- Too much text in images
+- Ignoring Stories and Reels
+- Only promotional content
+
+**Format tips:**
+- Reels get 2x reach of static posts
+- First frame of Reels must hook
+- Carousels: 10 slides with educational content
+- Use all Story features (polls, links, etc.)
+
+**Algorithm tips:**
+- Reels heavily prioritized over static posts
+- Saves and shares > likes
+- Stories keep you top of feed
+- Consistency matters more than perfection
+- Use all features (polls, questions, etc.)
+
+---
+
+## TikTok
+
+**Best for:** Brand awareness, younger audiences, viral potential
+**Audience:** 16-34, entertainment-focused
+**Posting frequency:** 1-4x per day
+**Best times:** 7-9am, 12-3pm, 7-11pm
+
+**What works:**
+- Native, unpolished content
+- Trending sounds and formats
+- Educational content in entertaining wrapper
+- POV and day-in-the-life content
+- Responding to comments with videos
+- Duets and stitches
+
+**What doesn't:**
+- Overly produced content
+- Ignoring trends
+- Hard selling
+- Repurposed horizontal video
+
+**Format tips:**
+- Hook in first 1-2 seconds
+- Keep it under 30 seconds to start
+- Vertical only (9:16)
+- Use trending sounds
+- Post consistently to train algorithm
+
+---
+
+## Facebook
+
+**Best for:** Communities, local businesses, older demographics, groups
+**Audience:** 25-55+, community-oriented
+**Posting frequency:** 1-2x per day
+**Best times:** 1-4pm weekdays
+
+**What works:**
+- Facebook Groups (community)
+- Native video
+- Live video
+- Local content and events
+- Discussion-prompting questions
+
+**What doesn't:**
+- Links to external sites (reach killer)
+- Pure promotional content
+- Ignoring comments
+- Cross-posting from other platforms without adaptation