Add sovereign room to MemPalace fleet taxonomy

Refs #1116. Adds 'sovereign' room for cataloging Alexander Whitestone's
requests and responses as dated, retrievable artifacts.

Room config:
- key: sovereign, available to all wizards
- Naming convention: YYYY-MM-DD_HHMMSS_<topic>.md
- Running INDEX.md for chronological catalog
- Fleet-wide tunnel for cross-wizard search

mempalace/rooms.yaml

@@ -98,6 +98,15 @@ optional_rooms:
     purpose: Catch-all for artefacts not yet assigned to a named room
     wizards: ["*"]
 
+  - key: sovereign
+    label: Sovereign
+    purpose: Artifacts of Alexander Whitestone's requests, directives, and conversation history
+    wizards: ["*"]
+    conventions:
+      naming: "YYYY-MM-DD_HHMMSS_<topic>.md"
+      index: "INDEX.md"
+      description: "Each artifact is a dated record of a request from Alexander and the wizard's response. The running INDEX.md provides a chronological catalog."
+
 # Tunnel routing table
 # Defines which room pairs are connected across wizard wings.
 # A tunnel lets `recall <query> --fleet` search both wings at once.
@@ -112,3 +121,5 @@ tunnels:
     description: Fleet-wide issue and PR knowledge
   - rooms: [experiments, experiments]
     description: Cross-wizard spike and prototype results
+  - rooms: [sovereign, sovereign]
+    description: Alexander's requests and responses shared across all wizards