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-19/ci.md

@@ -1,3 +1,12 @@
+---
+title: "Sprint 19 — CI Briefing"
+description: "Test runner scripts, protocol version handshake, IPC round-trip benchmark"
+type: sprint
+status: archived
+sprint: 19
+team: "ci"
+---
+
 # Sprint 19: Persist — CI Tasks
 
 **Goal:** The player can save and resume a game session with per-game directories; the simulation tier system gains eviction and scope pinning; and the first test infrastructure ships with information boundary validation and IPC hardening.

docs/sprints/sprint-19/client.md

@@ -1,3 +1,12 @@
+---
+title: "Sprint 19 — Client Briefing"
+description: "Save/load client UI, game session management, GDScript test framework"
+type: sprint
+status: archived
+sprint: 19
+team: "client"
+---
+
 # Sprint 19: Persist — Client Tasks
 
 **Goal:** The player can save and resume a game session with per-game directories; the simulation tier system gains eviction and scope pinning; and the first test infrastructure ships with information boundary validation and IPC hardening.

docs/sprints/sprint-19/joint.md

@@ -1,3 +1,12 @@
+---
+title: "Sprint 19 — Joint Briefing"
+description: "Save/load IPC protocol coordination, handshake wire format, fixture file format"
+type: sprint
+status: archived
+sprint: 19
+team: "joint"
+---
+
 # Sprint 19: Persist — Joint Briefing
 
 **Goal:** The player can save and resume a game session with per-game directories; the simulation tier system gains eviction and scope pinning; and the first test infrastructure ships with information boundary validation and IPC hardening.

docs/sprints/sprint-19/server.md

@@ -1,3 +1,12 @@
+---
+title: "Sprint 19 — Server Briefing"
+description: "Save/load ECS extraction, state serialization, timestamp-based eviction, scope tags"
+type: sprint
+status: archived
+sprint: 19
+team: "server"
+---
+
 # Sprint 19: Persist — Server Tasks
 
 **Goal:** The player can save and resume a game session with per-game directories; the simulation tier system gains eviction and scope pinning; and the first test infrastructure ships with information boundary validation and IPC hardening.