Add initial README and architecture decision records for venue-driven simulation game

- Introduced README.md outlining game concept, mechanics, and planned venues.
- Added ADRs for venue-driven architecture, de-escalation-first model, explicit access verification, local single-player focus, event-based incident recording, and choice of Godot 4 with GDScript.

docs/adr/0004-local-single-player-first.md

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+# ADR-0004: Local single-player first
+
+- **Status:** Accepted
+- **Date:** TBD
+
+## Context
+
+The project is at the planning stage and no engine, backend, or multiplayer requirement has been established. The core experience is a single guard making decisions during a short shift. Early development needs fast iteration on rules, NPC behavior, UI, and scenario content.
+
+## Decision
+
+Build the first playable version as a local single-player game. Keep simulation, presentation, content, and shift results in one client process. Do not require an online service or multiplayer layer for the initial prototype.
+
+## Consequences
+
+### Positive
+
+- Reduces infrastructure and deployment complexity.
+- Makes deterministic scenario testing easier.
+- Allows the team to validate the core game loop before committing to networking.
+- Keeps the first vertical slice small.
+
+### Negative
+
+- Multiplayer and online analytics are deferred.
+- Some future features may require refactoring if they depend on network authority.
+- Local persistence and platform support still need to be designed later.
+
+## Alternatives considered
+
+- **Multiplayer-first:** Rejected because it adds complexity before the single-player loop is proven.
+- **Backend-first simulation:** Rejected because the planned game does not currently require a service or shared world.