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-13/audio.md

@@ -1,3 +1,12 @@
+---
+title: "Sprint 13 — Audio Briefing"
+description: "NPC conversation murmur asset, World SFX bus wiring"
+type: sprint
+status: archived
+sprint: 13
+team: "audio"
+---
+
 # Sprint 13: Sound — Audio Tasks
 
 **Goal:** Wire the full audio architecture end-to-end — AudioManager, zone crossfades, dip profiles, recognition chime, and conversation murmur — and complete v0.1 content authoring so opening hooks, tutorial monologue, and all content packs are done.

docs/sprints/sprint-13/client.md

@@ -1,3 +1,12 @@
+---
+title: "Sprint 13 — Client Briefing"
+description: "AudioManager 5-bus implementation, zone crossfade, audio dip profiles, recognition chime"
+type: sprint
+status: archived
+sprint: 13
+team: "client"
+---
+
 # Sprint 13: Sound — Client Tasks
 
 **Goal:** Wire the full audio architecture end-to-end — AudioManager, zone crossfades, dip profiles, recognition chime, and conversation murmur — and complete v0.1 content authoring so opening hooks, tutorial monologue, and all content packs are done.

docs/sprints/sprint-13/joint.md

@@ -1,3 +1,12 @@
+---
+title: "Sprint 13 — Joint Briefing"
+description: "Full audio architecture wiring, zone crossfades, dip profiles, v0.1 content completion"
+type: sprint
+status: archived
+sprint: 13
+team: "joint"
+---
+
 # Sprint 13: Sound — Joint / Integration Notes
 
 **Goal:** Wire the full audio architecture end-to-end — AudioManager, zone crossfades, dip profiles, recognition chime, and conversation murmur — and complete v0.1 content authoring so opening hooks, tutorial monologue, and all content packs are done.

docs/sprints/sprint-13/server.md

@@ -1,3 +1,12 @@
+---
+title: "Sprint 13 — Server Briefing"
+description: "Gauntlet rooms (Sound Lab, Decay Observatory, Shift Change), OQ-09 zone temperature"
+type: sprint
+status: archived
+sprint: 13
+team: "server"
+---
+
 # Sprint 13: Sound — Server Tasks
 
 **Goal:** Wire the full audio architecture end-to-end — AudioManager, zone crossfades, dip profiles, recognition chime, and conversation murmur — and complete v0.1 content authoring so opening hooks, tutorial monologue, and all content packs are done.

docs/sprints/sprint-13/visual.md

@@ -1,3 +1,12 @@
+---
+title: "Sprint 13 — Visual Briefing"
+description: "Monologue display system visual spec"
+type: sprint
+status: archived
+sprint: 13
+team: "visual"
+---
+
 # Sprint 13: Sound — Visual Tasks
 
 **Goal:** Wire the full audio architecture end-to-end — AudioManager, zone crossfades, dip profiles, recognition chime, and conversation murmur — and complete v0.1 content authoring so opening hooks, tutorial monologue, and all content packs are done.