docs(docs): add frontmatter to map-authoring, npc-ai, observer-snapshot, and save-load workshop briefs

Standardized YAML frontmatter on 4 workshop brief files.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

docs/workshops/map-authoring-pipeline/workshop-brief.md

@@ -1,3 +1,12 @@
+---
+title: "Map Authoring Pipeline Workshop Brief"
+description: "Define how v0.1 hand-crafted tile maps are authored, stored, and loaded by server and client."
+type: workshop
+status: archived
+workshop: "map-authoring-pipeline"
+created: 2026-02-11
+---
+
 # Map Authoring Pipeline Workshop Brief
 
 **Goal:** Define how v0.1 maps (5-8 hand-crafted buildings per world, 150x150 tiles, 2-3 z-levels) are authored, stored, and loaded by both server and client.

docs/workshops/npc-ai-state-machines/workshop-brief.md

@@ -1,3 +1,12 @@
+---
+title: "NPC AI State Machines Workshop Brief"
+description: "Specify the four Background-tier NPC state machines — schedule, mood, relationships, and job — with states, transitions, and tick budgets."
+type: workshop
+status: archived
+workshop: "npc-ai-state-machines"
+created: 2026-02-11
+---
+
 # NPC AI State Machines Workshop Brief
 
 **Goal:** Specify the 4 Background-tier state machines (schedule, mood, relationships, job) — states, transitions, day phase integration, and tick budgets.

docs/workshops/observer-snapshot-pipeline/workshop-brief.md

@@ -1,3 +1,12 @@
+---
+title: "Observer Snapshot Generation Pipeline Workshop Brief"
+description: "Design the server-side pipeline that computes per-tick ObserverSnapshot from world state via spatial queries, LOS, and sound propagation."
+type: workshop
+status: archived
+workshop: "observer-snapshot-pipeline"
+created: 2026-02-11
+---
+
 # Observer Snapshot Generation Pipeline Workshop Brief
 
 **Goal:** Design the algorithm for "what does entity X perceive this tick?" — the server-side pipeline that computes ObserverSnapshot from world state.

docs/workshops/save-load-architecture/workshop-brief.md

@@ -1,3 +1,12 @@
+---
+title: "Save/Load Architecture Workshop Brief"
+description: "Design the save/load system — serialization strategy, versioning, migration, and integration with tier serialization."
+type: workshop
+status: archived
+workshop: "save-load-architecture"
+created: 2026-02-11
+---
+
 # Save/Load Architecture Workshop Brief
 
 **Goal:** Design the save/load system — serialization strategy, versioning, migration, and relationship to tier serialization.