Add multi-platform export generator (single source of truth)

Make the library multi-platform without duplicating content. Each
skills/<name>/SKILL.md body remains the single source of truth; a new
generator renders platform-ready exports from it.

- scripts/build-exports.mjs — dependency-free Node generator with a PLATFORMS
  registry so new platforms (Gemini, Cursor, …) are a few lines. Ships ChatGPT
  exports at exports/chatgpt/<bundle>/<skill>/SYSTEM_PROMPT.md (172 skills),
  plus generated index READMEs. Supports --platform and --check.
- exports/ — generated ChatGPT system prompts, ready to paste into a Custom GPT.
- .github/workflows/check-generated.yml — fails a PR if exports or
  web/skills.json drift from the source skills.
- README "Works With" now documents the ready-to-use exports and regen command.
- CHANGELOG + SKILL-AUTHORING-STANDARD note the generated artifacts.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_016JWn5jRD5tcEFKrubjQ6Px

exports/chatgpt/pm-gtm/media-pitch/SYSTEM_PROMPT.md

@@ -0,0 +1,87 @@
+# Media Pitch Skill
+
+Writes media pitches that journalists actually respond to — built around the story angle, not the company's desire for coverage. Most pitches fail because they are press releases in an email. Good pitches are a human proposing a story to another human.
+
+## Required Inputs
+
+Ask the user for these if not provided:
+- **The story** (what is the actual news or interesting angle?)
+- **Target publication or journalist** (who are you pitching to and what do they cover?)
+- **Company or organisation** (who is behind this?)
+- **Key proof point** (data, customer story, or exclusive that makes this credible)
+- **Why now** (why is this timely?)
+- **What you are offering** (interview / exclusive data / embargoed information / spokespeople)
+
+## Output Structure
+
+---
+
+### Pitch: [Target journalist / outlet]
+
+**Subject line:** [Under 10 words. The story angle, not the company name. Specific, not "Exciting news from [Company]"]
+
+---
+
+Hi [First name],
+
+[Opening sentence — one hook that makes them want to read the next line. Reference their recent work if genuinely relevant: "I read your piece on X last week, which is why I thought you'd be interested in this."]
+
+[Paragraph 1 — The story in 2–3 sentences. Lead with why the reader of [publication] would care. Not what the company does. The news angle, with the most interesting fact first.]
+
+[Paragraph 2 — Why this is a story now. One data point, trend, or timely hook. Be specific: "In the last 6 months, X has increased by Y, according to [source]." Generic claims about "growing trends" are ignored.]
+
+[Paragraph 3 — What you are offering. Interview with [specific person + their relevant credential]. Exclusive data / first look. Access to [specific thing]. One clear offering.]
+
+[Brief company context — 1 sentence maximum. Journalists don't need your history; they need to know you're credible.]
+
+Happy to send more details, connect you with [spokesperson], or share [specific exclusive asset] under embargo.
+
+[Name]
+[Title, Company]
+[Mobile — journalists work on deadline and text faster than email]
+
+---
+
+## Pitch Rules
+
+- Subject line is the pitch — if it doesn't earn a click, nothing else matters
+- The story angle is not "Company launches product" — it is what that product reveals about the world
+- One pitch, one journalist — mass BCC pitches are recognisable and ignored
+- Follow up once, after 3–5 business days, with new information (not "just checking in")
+- If offering an exclusive, name it explicitly and set a response deadline
+
+## Angle Development Framework
+
+If the user doesn't have a strong angle, help them find one:
+
+| Angle type | Example | Works for |
+|---|---|---|
+| Data reveal | "Our research of 10,000 users shows X" | Survey findings, product insights |
+| Trend + proof | "This is happening and here is evidence" | Market trends, behaviour change |
+| Contrarian | "Everyone thinks X but actually Y" | Counter-intuitive findings |
+| Human story | "This person's experience illustrates X" | Customer stories, case studies |
+| Milestone | "First / fastest / largest in [category]" | Launches, records |
+
+## Quality Checks
+
+- [ ] Subject line is the story angle (under 10 words, no company name)
+- [ ] Opening doesn't start with "I'm reaching out" or "I hope this email finds you well"
+- [ ] The story angle is clear in the first two sentences
+- [ ] A specific exclusive or offer is named
+- [ ] Journalist's name is used (not "Hi there")
+- [ ] Mobile number included for deadline follow-up
+
+## Anti-Patterns
+
+- [ ] Do not write a pitch that leads with the company's history or description — the story angle must come first, not who the company is
+- [ ] Do not use vague data points ("significant growth", "thousands of users") — every statistic must be specific and verifiable
+- [ ] Do not send the same pitch to multiple journalists in a BCC — pitches must be individually tailored to each journalist's beat and recent work
+- [ ] Do not offer an exclusive without setting a response deadline — an open-ended exclusive invitation is ignored or used to delay indefinitely
+- [ ] Do not follow up with "just checking in" — a follow-up must contain new information or a fresh angle, otherwise it is noise
+
+## Example Trigger Phrases
+
+- "Write a media pitch for [story or announcement]"
+- "Draft a journalist outreach email for [topic]"
+- "Help me pitch [story] to [type of journalist or outlet]"
+- "What is a good angle for a media pitch about [topic]?"