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-10/audio.md

@@ -1,3 +1,12 @@
+---
+title: "Sprint 10 — Audio Briefing"
+description: "Audio asset set — 8 minimum viable files via Stable Audio Open"
+type: sprint
+status: archived
+sprint: 10
+team: "audio"
+---
+
 # Sprint 10: Prove — Audio Tasks
 
 **Goal:** Expand the Gauntlet test suite with new rooms and cross-room scenarios, wire the audio architecture end-to-end, and complete client UX polish from Sprint 9 carry-overs — proving the full system holds together.

docs/sprints/sprint-10/ci.md

@@ -1,3 +1,12 @@
+---
+title: "Sprint 10 — CI Briefing"
+description: "Performance baseline tooling, CI pipeline Gitea Actions, relationship consistency validation"
+type: sprint
+status: archived
+sprint: 10
+team: "ci"
+---
+
 # Sprint 10: Prove — CI Tasks
 
 **Goal:** Expand the Gauntlet test suite with new rooms and cross-room scenarios, wire the audio architecture end-to-end, and complete client UX polish from Sprint 9 carry-overs — proving the full system holds together.

docs/sprints/sprint-10/client.md

@@ -1,3 +1,12 @@
+---
+title: "Sprint 10 — Client Briefing"
+description: "Hub teleport UX, room reset UX, auto-checklist progress tracking"
+type: sprint
+status: archived
+sprint: 10
+team: "client"
+---
+
 # Sprint 10: Prove — Client Tasks
 
 **Goal:** Expand the Gauntlet test suite with new rooms and cross-room scenarios, wire the audio architecture end-to-end, and complete client UX polish from Sprint 9 carry-overs — proving the full system holds together.

docs/sprints/sprint-10/joint.md

@@ -1,3 +1,12 @@
+---
+title: "Sprint 10 — Joint Briefing"
+description: "Gauntlet expansion, audio architecture wiring, client UX polish carry-overs"
+type: sprint
+status: archived
+sprint: 10
+team: "joint"
+---
+
 # Sprint 10: Prove — Joint / Integration
 
 **Goal:** Expand the Gauntlet test suite with new rooms and cross-room scenarios, wire the audio architecture end-to-end, and complete client UX polish from Sprint 9 carry-overs — proving the full system holds together.

docs/sprints/sprint-10/server.md

@@ -1,3 +1,12 @@
+---
+title: "Sprint 10 — Server Briefing"
+description: "Gauntlet room expansion, hub teleport action, replay loading, content scaling test"
+type: sprint
+status: archived
+sprint: 10
+team: "server"
+---
+
 # Sprint 10: Prove — Server Tasks
 
 **Goal:** Expand the Gauntlet test suite with new rooms and cross-room scenarios, wire the audio architecture end-to-end, and complete client UX polish from Sprint 9 carry-overs — proving the full system holds together.