README "Try it" section links the Sandbox download #121

Parent

#27 (M6 General sensors)

Spec: docs/specs/general-sensors.md (added by PR #111; read it there until it merges). Parent: #27.

What to build

A "Try it" section at the top of the README links the sandbox-app-v1 Release and gives the steps past Windows SmartScreen and macOS Gatekeeper (System Settings → Privacy & Security → Open Anyway), none needing a terminal. AGENTS.md keeps the commands for people with a checkout. CONTEXT.md's Sandbox entry gains the app ("one command" and a double-click). Spec decisions 7 and 8.

Acceptance criteria

• README top section "Try it" links the Release and gives both unsigned-app warning steps without a terminal.
• CONTEXT.md Sandbox entry mentions the app; AGENTS.md still lists the checkout commands.
• scripts/check.sh passes.

Blockers are native links.