chore: track all project map and index files

Add generated .pi-map.md and .pi-map.index.md files across the repository
so the project navigation maps are shared and versioned. These artifacts
are maintained by project_map_init/patch/validate and must be kept in
sync with source edits.

Note: .cache/ remains ignored (added in previous commit).

.opencode/skills/.pi-map.index.md

@@ -0,0 +1,29 @@
+# .opencode/skills (index)
+dir: .opencode/skills
+
+## role
+Contains reusable skill modules that provide specific capabilities or integrations for the OpenCode agent framework.
+## parent
+index: .opencode/.pi-map.index.md
+map: .opencode/.pi-map.md
+## children
+- .opencode/skills/openspec-apply-change
+  index: .opencode/skills/openspec-apply-change/.pi-map.index.md
+  map: .opencode/skills/openspec-apply-change/.pi-map.md
+- .opencode/skills/openspec-archive-change
+  index: .opencode/skills/openspec-archive-change/.pi-map.index.md
+  map: .opencode/skills/openspec-archive-change/.pi-map.md
+- .opencode/skills/openspec-explore
+  index: .opencode/skills/openspec-explore/.pi-map.index.md
+  map: .opencode/skills/openspec-explore/.pi-map.md
+- .opencode/skills/openspec-propose
+  index: .opencode/skills/openspec-propose/.pi-map.index.md
+  map: .opencode/skills/openspec-propose/.pi-map.md
+## files
+## links
+index: .opencode/skills/.pi-map.index.md
+map: .opencode/skills/.pi-map.md
+## workflows
+-
+## dirty
+-