Set up DOTS + Netcode for Entities foundation

One-time stack setup per Docs/dots-setup-task.md (Unity 6.4.7 / 6000.4.7f1).
Packages: entities 6.4.0, entities.graphics 6.4.0, netcode 1.13.2, physics 1.4.6.

- Assets/_Project asmdef split: ProjectM.Simulation/Client/Server/Authoring (root ns ProjectM)
- GameBootstrap : ClientServerBootstrap; verified separate client + server worlds in Play Mode
- Gameplay subscene wired into SampleScene as a baking target
- Heartbeat component + Burst ISystem; EditMode smoke test green (1/1)
- In-repo Obsidian vault (Docs/Vault) incl. DR-001 (plain-Entities test over internal NetCodeTestWorld)
- Portable .mcp.json (basic-memory + serena via ${CLAUDE_PROJECT_DIR}); CLAUDE.md conventions
- .gitignore for DOTS baking cache + machine-local config

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

Docs/Vault/_Templates/Session_Log_Template.md

@@ -0,0 +1,23 @@
+---
+permalink: gamevault/templates/session-log-template
+---
+
+---
+date: {{date:YYYY-MM-DD}}
+type: session
+tags: [session]
+---
+
+# Session {{date:YYYY-MM-DD}} — <title>
+
+## Goal
+
+## Done
+
+## Decisions
+
+- <link any DR-### created this session>
+
+## Open / deferred
+
+## Next