docs(docs): add frontmatter to all sprint briefings

Standardized YAML frontmatter on all 115 sprint briefing files across
sprints 1-26 with title, description, type, status, sprint number, and
team fields.

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

docs/sprints/sprint-25/copy.md

@@ -1,3 +1,12 @@
+---
+title: "Sprint 25 — Copy Briefing"
+description: "Zone identity spec, Krenn culture profile"
+type: sprint
+status: archived
+sprint: 25
+team: "copy"
+---
+
 # Sprint 25: Emerge — Copy Tasks
 
 **Goal:** Prove the generator can extrapolate from minimal input — a rural Krenn area AND an industrial Krenn zone from zone type and culture profile alone, no per-location spec. Two zone types, one culture, side-by-side comparison.

docs/sprints/sprint-25/joint.md

@@ -1,3 +1,12 @@
+---
+title: "Sprint 25 — Joint Briefing"
+description: "Generator proof-of-life coordination, zone spec handoff, throwaway render test"
+type: sprint
+status: archived
+sprint: 25
+team: "joint"
+---
+
 # Sprint 25: Emerge — Joint
 
 **Confidence: 15%.** This sprint is exploratory — we learn whether the approach works, not whether we can ship it. Declare what we learned, not victory.

docs/sprints/sprint-25/server.md

@@ -1,3 +1,12 @@
+---
+title: "Sprint 25 — Server Briefing"
+description: "NpcBlueprint struct design, template assembly generator"
+type: sprint
+status: archived
+sprint: 25
+team: "server"
+---
+
 # Sprint 25: Emerge — Server Tasks
 
 **Goal:** Prove the generator can extrapolate from minimal input — a rural Krenn area AND an industrial Krenn zone from zone type and culture profile alone, no per-location spec. Two zone types, one culture, side-by-side comparison.