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-7/audio.md

@@ -1,3 +1,12 @@
+---
+title: "Sprint 7 — Audio Briefing"
+description: "6 interaction audio assets — cursor hover, weapon mode, fog recognition, dialogue"
+type: sprint
+status: archived
+sprint: 7
+team: "audio"
+---
+
 # Sprint 7: Talk — Audio Tasks
 
 **Goal:** Complete interaction UI layer and activate basic dialogue system with NPC conversations.

docs/sprints/sprint-7/client.md

@@ -1,3 +1,12 @@
+---
+title: "Sprint 7 — Client Briefing"
+description: "Sprint 6 UI carry-over (cursor, fog shader, interaction list, radial menu, inventory, stance)"
+type: sprint
+status: archived
+sprint: 7
+team: "client"
+---
+
 # Sprint 7: Talk — Client Tasks
 
 **Goal:** Complete interaction UI layer and activate basic dialogue system with NPC conversations.

docs/sprints/sprint-7/copy.md

@@ -1,3 +1,12 @@
+---
+title: "Sprint 7 — Copy Briefing"
+description: "Archetype evidence presentation spec — detective case file vs smuggler notebook"
+type: sprint
+status: archived
+sprint: 7
+team: "copy"
+---
+
 # Sprint 7: Talk — Copy Tasks
 
 **Goal:** Complete interaction UI layer and activate basic dialogue system with NPC conversations.

docs/sprints/sprint-7/joint.md

@@ -1,3 +1,12 @@
+---
+title: "Sprint 7 — Joint Briefing"
+description: "Sprint 6 UI carry-over completion, dialogue system foundation, NPC conversations"
+type: sprint
+status: archived
+sprint: 7
+team: "joint"
+---
+
 # Sprint 7: Talk — Joint Integration
 
 **Goal:** Complete interaction UI layer and activate basic dialogue system with NPC conversations.

docs/sprints/sprint-7/server.md

@@ -1,3 +1,12 @@
+---
+title: "Sprint 7 — Server Briefing"
+description: "Cognitive delay system, line pool format, YAML hot-reload, InteractionMemory KG schema"
+type: sprint
+status: archived
+sprint: 7
+team: "server"
+---
+
 # Sprint 7: Talk — Server Tasks
 
 **Goal:** Complete interaction UI layer and activate basic dialogue system with NPC conversations.