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.

archive/src/media_library_viewer/services/.pi-map.index.md

@@ -0,0 +1,21 @@
+# archive/src/media_library_viewer/services (index)
+dir: archive/src/media_library_viewer/services
+
+## role
+Application service layer that coordinates domain logic and external clients into reusable, UI-agnostic media library operations.
+## parent
+index: archive/src/media_library_viewer/.pi-map.index.md
+map: archive/src/media_library_viewer/.pi-map.md
+## children
+-
+## files
+- __init__.py
+- media_index.py
+## links
+index: archive/src/media_library_viewer/services/.pi-map.index.md
+map: archive/src/media_library_viewer/services/.pi-map.md
+## workflows
+- change services behavior
+  read: __init__.py, media_index.py
+## dirty
+-

archive/src/media_library_viewer/services/.pi-map.md

@@ -0,0 +1,28 @@
+# archive/src/media_library_viewer/services
+dir: archive/src/media_library_viewer/services
+
+index: archive/src/media_library_viewer/services/.pi-map.index.md
+
+## role
+Application service layer that coordinates domain logic and external clients into reusable, UI-agnostic media library operations.
+## files
+- __init__.py | Marks the directory as a Python package and documents it as the application services layer for coordinating clients/domain logic into reusable operations.
+- media_index.py | Provides a UI-agnostic SQLite-backed media inventory service that indexes, queries, and manages Jellyfin media metadata with filtering, sorting, and pagination capabilities. | exp: class:MediaIndexStatus, class:MediaIndex, method:__init__(self, db_path), call:Path, call:self.db_path.parent.mkdir, method:connect(self) → sqlite3.Connection, call:sqlite3.connect, method:init_schema(self) → None, call:self.connect, call:conn.executescript, method:set_metadata(self, key: str, value: str | int | float) → None, call:self.init_schema, call:self.connect, call:conn.execute, call:str, method:replace_items(self, rows: Iterable[dict[str, Any]]) → int, call:self.init_schema, call:list, call:",".join, call:len, call:self.connect, call:conn.execute, call:conn.executemany, call:','.join, call:row.get, call:str, call:int, call:time.time, method:status(self) → MediaIndexStatus, call:self.db_path.exists, call:MediaIndexStatus, call:self.connect, call:int, call:conn.execute("SELECT COUNT(*) FROM media_items").fetchone, call:conn.execute("SELECT value FROM index_metadata WHERE key='updated_at'").fetchone, call:conn.execute("SELECT value FROM index_metadata WHERE key='build_duration_seconds'").fetchone, call:str(updated_row[0]).isdigit, call:time.strftime, call:time.localtime, call:float, method:query(self, library_id, library_ids, media_types, search, hdr_filter, sort_key, sort_order, limit, offset) → tuple[list[dict[str, Any]], int], call:self.init_schema, call:where.append, call:",".join, call:len, call:params.extend, call:params.append, call:search.lower, call:" AND ".join, call:SORT_COLUMNS.get, call:self.connect, call:int, call:conn.execute("SELECT COUNT(*) FROM media_items" + where_sql, params).fetchone, call:conn.execute( "SELECT * FROM media_items" + where_sql + order_sql + " LIMIT ? OFFSET ?", [*params, int(limit), int(offset)], ).fetchall, call:display_media_row, call:dict, func:build_media_index(client: JellyfinClient, user_id: str, libraries: list[dict[str, Any]], index, page_size) → int, call:MediaIndex, call:time.perf_counter, call:library.get, call:client.items, call:response.get, call:normalized_rows.extend, call:normalize_media_item, call:len, call:int, call:index.replace_items, call:index.set_metadata | dep: sqlite3, time, dataclasses, pathlib, typing, media_library_viewer.clients.jellyfin, media_library_viewer.domain.media, media_library_viewer.clients.jellyfin.JellyfinClient, media_library_viewer.domain.media.display_media_row, media_library_viewer.domain.media.normalize_media_item
+## arch
+Service-oriented pattern with SQLite-backed indexing, query filtering, and pagination encapsulated behind a single cohesive media index service module.
+## tags
+media, call:conn.execute, index, call:self.connect, schema, call:int, init, status
+## symbols
+- MediaIndexStatus
+- MediaIndex
+- __init__
+- connect
+- init_schema
+- set_metadata
+- replace_items
+- status
+## workflows
+- change services behavior
+  read: __init__.py, media_index.py
+## dirty
+-