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/01_Vision/Pillars.md

@@ -0,0 +1,24 @@
+---
+tags:
+- vision
+- pillars
+status: draft
+updated: 2026-05-29
+permalink: gamevault/01-vision/pillars
+---
+
+# Design Pillars & Locked Decisions
+
+> The few non-negotiables every system must serve. Keep this short; promote only decisions that are truly locked.
+
+## Pillars
+
+- _TBD — define the 3–5 experiential pillars of Project M._
+
+## Locked decisions
+
+- **Tech stack:** Unity DOTS (Entities) + Netcode for Entities — server-authoritative, input-only clients, client prediction. Established [[2026-05-29_Project_Setup]].
+
+## Related
+
+- Decision records: `07_Sessions/_Decisions/`