refactor(examples): move example files to data/examples

Relocates all example YAML files from the `examples/` directory to `data/examples/`.
Updates `docs/schema-design.md` to reflect the new path for example files.

data/examples/theme.yaml

@@ -0,0 +1,59 @@
+# Example Theme Entry
+# Themes customize the OpenCode editor appearance.
+# Place actual entries in: data/themes/your-theme-name.yaml
+
+# ============================================================================
+# REQUIRED FIELDS
+# ============================================================================
+
+name: Example Dark Theme
+repo: https://github.com/example/opencode-example-theme
+tagline: A beautiful dark theme with vibrant accents
+description: |
+  A dark theme designed for extended coding sessions.
+  Features high contrast syntax highlighting and
+  carefully chosen colors to reduce eye strain.
+
+# ============================================================================
+# OPTIONAL FIELDS
+# ============================================================================
+
+# Scope defines where the extension can be installed (defaults to [global])
+# Themes are typically global-only
+scope:
+  - global   # ~/.config/opencode/themes/
+
+tags:
+  - dark
+  - high-contrast
+  - syntax-highlighting
+
+min_version: "1.0.0"
+
+homepage: https://example.com/themes/dark
+
+installation: |
+  ## Installation
+
+  ### Global
+  ```bash
+  # Download theme JSON
+  curl -o ~/.config/opencode/themes/example-dark.json \
+    https://raw.githubusercontent.com/example/opencode-example-theme/main/theme.json
+  ```
+
+  ## Configuration
+  Add to your `opencode.json`:
+  ```json
+  {
+    "theme": "example-dark"
+  }
+  ```
+
+  ## Files Modified
+  - `~/.config/opencode/themes/example-dark.json`
+  - `~/.config/opencode/opencode.json` (theme reference)
+
+  ## Removal
+  1. Delete `~/.config/opencode/themes/example-dark.json`
+  2. Change `theme` in `opencode.json` to another theme