chore: archive observability-service-registry, track pi-map artifacts

- Archive the completed observability-service-registry SDD change into
  openspec/changes/archive/ (delivered across 5 slices; only
  jellyfin-service-registry remains active).
- Stop ignoring .pi-map.md / .pi-map.index.md so the navigation maps are
  versioned alongside the code, and add the regenerated map pairs repo-wide.

.opencode/skills/openspec-apply-change/.pi-map.index.md

@@ -0,0 +1,19 @@
+# .opencode/skills/openspec-apply-change (index)
+dir: .opencode/skills/openspec-apply-change
+
+## role
+Provides a structured skill definition for implementing OpenSpec changes through a schema-driven workflow with progress tracking.
+## parent
+index: .opencode/skills/.pi-map.index.md
+map: .opencode/skills/.pi-map.md
+## children
+-
+## files
+- SKILL.md
+## links
+index: .opencode/skills/openspec-apply-change/.pi-map.index.md
+map: .opencode/skills/openspec-apply-change/.pi-map.md
+## workflows
+-
+## dirty
+-

.opencode/skills/openspec-apply-change/.pi-map.md

@@ -0,0 +1,19 @@
+# .opencode/skills/openspec-apply-change
+dir: .opencode/skills/openspec-apply-change
+
+index: .opencode/skills/openspec-apply-change/.pi-map.index.md
+
+## role
+Provides a structured skill definition for implementing OpenSpec changes through a schema-driven workflow with progress tracking.
+## files
+- SKILL.md | Defines a skill for implementing tasks from an OpenSpec change using a schema-driven workflow with progress tracking and contextual file reading. | dep: openspec CLI, AskUserQuestion tool
+## arch
+Documentation-based skill specification using markdown with defined workflow steps, schema references, and contextual file reading rules.
+## tags
+skill, defines, implementing, tasks, openspec, change, schema, driven
+## symbols
+-
+## workflows
+-
+## dirty
+-