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-propose/.pi-map.index.md

@@ -0,0 +1,19 @@
+# .opencode/skills/openspec-propose (index)
+dir: .opencode/skills/openspec-propose
+
+## role
+Provides an AI assistant skill that automates the openspec proposal workflow by scaffolding directories and generating structured artifacts (proposals, designs, tasks).
+## parent
+index: .opencode/skills/.pi-map.index.md
+map: .opencode/skills/.pi-map.md
+## children
+-
+## files
+- SKILL.md
+## links
+index: .opencode/skills/openspec-propose/.pi-map.index.md
+map: .opencode/skills/openspec-propose/.pi-map.md
+## workflows
+-
+## dirty
+-

.opencode/skills/openspec-propose/.pi-map.md

@@ -0,0 +1,19 @@
+# .opencode/skills/openspec-propose
+dir: .opencode/skills/openspec-propose
+
+index: .opencode/skills/openspec-propose/.pi-map.index.md
+
+## role
+Provides an AI assistant skill that automates the openspec proposal workflow by scaffolding directories and generating structured artifacts (proposals, designs, tasks).
+## files
+- SKILL.md | Defines an AI assistant skill that automates proposing new changes by scaffolding a directory, generating dependent artifacts (proposal, design, tasks), and tracking progress through a structured workflow using the openspec CLI. | dep: openspec CLI, AskUserQuestion tool, TodoWrite tool
+## arch
+Skill-definition pattern using a declarative markdown document (SKILL.md) that encodes a step-by-step procedural workflow with CLI integration conventions.
+## tags
+skill, defines, assistant, automates, proposing, new, changes, scaffolding
+## symbols
+-
+## workflows
+-
+## dirty
+-