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.

.claude/.pi-map.index.md

@@ -0,0 +1,20 @@
+# .claude (index)
+dir: .claude
+
+## role
+Configuration directory for the Claude AI assistant, storing project-specific settings, instructions, and behavioral guidelines.
+## parent
+index: ./.pi-map.index.md
+map: ./.pi-map.md
+## children
+- .claude/skills
+  index: .claude/skills/.pi-map.index.md
+  map: .claude/skills/.pi-map.md
+## files
+## links
+index: .claude/.pi-map.index.md
+map: .claude/.pi-map.md
+## workflows
+-
+## dirty
+-

.claude/.pi-map.md

@@ -0,0 +1,18 @@
+# .claude
+dir: .claude
+
+index: .claude/.pi-map.index.md
+
+## role
+Configuration directory for the Claude AI assistant, storing project-specific settings, instructions, and behavioral guidelines.
+## files
+## arch
+Flat configuration structure containing markdown/YAML files that define custom commands, project context, and operational rules for Claude's interactions with the codebase.
+## tags
+-
+## symbols
+-
+## workflows
+-
+## dirty
+-

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

@@ -0,0 +1,20 @@
+# .claude/skills (index)
+dir: .claude/skills
+
+## role
+Directory containing custom skill definitions and capability instructions for the Claude AI assistant integration.
+## parent
+index: .claude/.pi-map.index.md
+map: .claude/.pi-map.md
+## children
+- .claude/skills/sift-backlog
+  index: .claude/skills/sift-backlog/.pi-map.index.md
+  map: .claude/skills/sift-backlog/.pi-map.md
+## files
+## links
+index: .claude/skills/.pi-map.index.md
+map: .claude/skills/.pi-map.md
+## workflows
+-
+## dirty
+-

.claude/skills/.pi-map.md

@@ -0,0 +1,18 @@
+# .claude/skills
+dir: .claude/skills
+
+index: .claude/skills/.pi-map.index.md
+
+## role
+Directory containing custom skill definitions and capability instructions for the Claude AI assistant integration.
+## files
+## arch
+Flat configuration file structure defining modular skill behaviors and prompts used to extend Claude's domain-specific abilities.
+## tags
+-
+## symbols
+-
+## workflows
+-
+## dirty
+-

.claude/skills/sift-backlog/.pi-map.index.md

@@ -0,0 +1,19 @@
+# .claude/skills/sift-backlog (index)
+dir: .claude/skills/sift-backlog
+
+## role
+Defines a Claude skill workflow for triaging, organizing, and activating backlog tasks into actionable plans using the `sf` CLI tool.
+## parent
+index: .claude/skills/.pi-map.index.md
+map: .claude/skills/.pi-map.md
+## children
+-
+## files
+- SKILL.md
+## links
+index: .claude/skills/sift-backlog/.pi-map.index.md
+map: .claude/skills/sift-backlog/.pi-map.md
+## workflows
+-
+## dirty
+-

.claude/skills/sift-backlog/.pi-map.md

@@ -0,0 +1,19 @@
+# .claude/skills/sift-backlog
+dir: .claude/skills/sift-backlog
+
+index: .claude/skills/sift-backlog/.pi-map.index.md
+
+## role
+Defines a Claude skill workflow for triaging, organizing, and activating backlog tasks into actionable plans using the `sf` CLI tool.
+## files
+- SKILL.md | Defines a workflow skill for triaging, organizing, and activating backlog tasks into actionable plans using the `sf` CLI tool. | dep: sf CLI (task, plan, dependency, update subcommands)
+## arch
+Single-file declarative skill definition following a prompt-driven workflow pattern with structured triage and activation instructions for Claude to execute.
+## tags
+skill, defines, workflow, triaging, organizing, activating, backlog, tasks
+## symbols
+-
+## workflows
+-
+## dirty
+-