Initial roadtrip wiki: Walldorf → IoM → Wild Atlantic Way

Route: Germany → Hoek van Holland ferry → England → Isle of Man → Ireland (Wild Atlantic Way cycling).
Includes location files, AI context, contributing guide, and README with ferry/logistics table.

CONTRIBUTING.md

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+# Contributing to the Roadtrip Wiki
+
+## Adding a New Location
+
+1. Create a new file in `locations/` — use the next available number prefix and a short kebab-case name
+2. Use the template from `.ai-context.md`
+3. Update the navigation table in `README.md`
+
+## Editing Recommendations
+
+- Keep recommendations opinionated and concise — "go here, skip that"
+- Add a `<!-- updated: YYYY-MM-DD -->` comment at the top of any section you update
+- Flag outdated info with `> **Note:** This may be outdated — verify before visiting`
+
+## File Naming
+
+```
+NN-location-name.md
+```
+
+Where `NN` is a two-digit number preserving route order.
+
+## Formatting
+
+- Use `>` blockquotes for quick-reference metadata at the top of each file
+- Use `##` for main sections, `###` for sub-sections (days, subsections)
+- Practical info (prices, hours, transport) goes in a `## Practical Info` section
+- Keep the main `## Must-See` list to 5–7 items max — this is curated, not exhaustive
+
+## AI Assistants
+
+See `.ai-context.md` for full context on the trip, the route, and conventions.