Windsurf + Aider targets, MCP server, and demo placement (#33)

Broadens both reach (more tools) and content types (an MCP server), continuing
the multi-platform story.

Windsurf + Aider:
- build-exports.mjs gains two platforms: exports/windsurf/*.md (workspace rules,
  trigger: model_decision) and exports/aider/*.md (conventions for `aider --read`).
  Now 5 platforms (ChatGPT, Gemini, Cursor, Windsurf, Aider).
- install.sh + bin/cli.mjs install both (windsurf -> .windsurf/rules, aider ->
  .aider/skills with a --read hint); generated README index is excluded from copies.
- One-line windsurf-install.sh / aider-install.sh wrappers for parity.

MCP server (new content type):
- mcp/server.mjs — zero-dependency stdio MCP server exposing list_skills,
  search_skills, get_skill. Published as a second bin (pm-claude-skills-mcp).
  Logs to stderr; reads bundled skills/ at startup. mcp/README.md documents
  client config.

Also: README hero "See it in action" demo placement (ready to swap in a GIF;
recording guide in web/docs-assets/README.md), Works-With table + exports +
install docs updated, CHANGELOG Unreleased. package.json files/bin updated.


Claude-Session: https://claude.ai/code/session_016JWn5jRD5tcEFKrubjQ6Px

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

exports/aider/pm-discovery/assumption-mapper/assumption-mapper.md

@@ -0,0 +1,61 @@
+# Assumption Mapper Skill
+
+Surface and prioritize the untested assumptions embedded in any product plan before development begins.
+
+## Required Inputs
+
+Ask the user for these if not provided:
+- **Product brief, PRD, or concept description** (even rough notes work)
+- **Stage** (concept / discovery / pre-build / post-launch — affects which assumptions matter most)
+
+## Process
+1. Read the provided brief, PRD, or concept description
+2. Extract assumptions across four categories:
+   - **Desirability** (do users want this?)
+   - **Feasibility** (can we build it?)
+   - **Viability** (will it sustain the business?)
+   - **Usability** (can users actually use it?)
+3. Score each assumption:
+   - Confidence (1-5): How sure are we this is true?
+   - Impact (1-5): How badly does the plan fail if this assumption is wrong?
+   - Priority = Impact − Confidence (higher = test first)
+4. **Validate completeness** — Ensure at least one assumption per category. If a category is empty, re-read the brief looking specifically for that type.
+5. Output a ranked list with recommended validation methods
+
+## Output Structure
+
+### Assumption Map: [Feature/Product Name]
+
+| Assumption | Category | Confidence | Impact | Priority | Validation Method |
+|------------|----------|------------|--------|----------|-------------------|
+| [assumption] | [type] | [1-5] | [1-5] | [score] | [method] |
+
+#### Critical Assumptions (Impact 4+ and Confidence 2 or below)
+[Flagged items with detailed validation recommendations]
+
+#### Top 3 Assumptions to Validate First
+[Detailed recommendations including specific research method, estimated effort, and what the result would change]
+
+## Example (Partial)
+
+Input: *"We're building a self-serve onboarding flow to reduce time-to-value for SMB customers."*
+
+| Assumption | Category | Confidence | Impact | Priority | Validation Method |
+|------------|----------|------------|--------|----------|-------------------|
+| SMB users can complete onboarding without human help | Usability | 2 | 5 | 3 | Unmoderated usability test (n=8) |
+| Faster onboarding correlates with higher retention | Viability | 3 | 4 | 1 | Cohort analysis of current onboarding times vs. 90-day retention |
+| The current onboarding is the primary reason for slow time-to-value | Desirability | 2 | 4 | 2 | User interviews with recent churned SMB accounts |
+
+## Anti-Patterns
+
+- [ ] Do not only surface desirability assumptions — feasibility and viability assumptions are equally likely to kill a product and are often overlooked
+- [ ] Do not assign high confidence to an assumption just because it hasn't been challenged yet — absence of evidence is not evidence
+- [ ] Do not recommend "user interviews" as the validation method for every assumption — some assumptions require quantitative data, competitive analysis, or technical spikes
+- [ ] Do not list assumptions that cannot be tested — every assumption in the map must have a plausible validation method, or it should be flagged as unknowable and treated as a risk
+
+## Quality Checks
+
+- [ ] At least one assumption per category (Desirability, Feasibility, Viability, Usability)
+- [ ] All Impact 4+ / Confidence 2− assumptions flagged as CRITICAL
+- [ ] Each validation method is specific (not just "do research" — name the method and sample size)
+- [ ] Priority scores are consistent (Impact − Confidence, higher = more urgent)