feat: ship workspace.json + setup-vault.sh for zero-config user experience

Users who clone the repo now get the full setup automatically:

- workspace.json tracked in git (removed from .gitignore)
  - Opens with Wiki Map canvas as default view
  - Graph view pre-configured: path:wiki filter, 5 color groups, proper physics
  - Obsidian reads this on first open before any state reset occurs

- bin/setup-vault.sh — one-time setup script
  - Writes correct graph.json (filter + colors)
  - Writes app.json (excludes plugin dirs from graph)
  - Writes appearance.json (enables vault-colors CSS)
  - Prints clear next-step instructions
  - Usage: bash bin/setup-vault.sh

- README updated: Option 1 now shows clone + setup.sh as recommended path
  - Clear explanation of what the script does
  - 2-minute setup flow vs manual configuration

Result: users clone, run setup.sh, open Obsidian — done.
Graph shows only wiki pages, color-coded, no noise.

.gitignore

@@ -1,5 +1,6 @@
 # Obsidian
-.obsidian/workspace.json
+# workspace.json is intentionally tracked — ships with pre-configured graph view
+# .obsidian/workspace.json
 .obsidian/workspace-mobile.json
 .obsidian/plugins/*/data.json
 .smart-connections/