[codex] Add OpenAI Game Builders WebGL submission lane

[YIFNEN]

Goal

Prepare Home Protector for the OpenAI Game Builders Seoul online qualifier with a public, immediately playable WebGL build before the 2026-08-26 submission deadline.

What changed

• isolates contest-only work on codex/openaigame2026
• adds a reproducible Unity WebGL build command that validates the project and required scenes
• configures a 1280×720 canvas, disabled WebGL compression, data caching, and hashed filenames
• makes legacy microphone code compile safely on WebGL
• routes native microphone activation and the browser F fallback through the same RequestPlayerActivation() path
• preserves native Editor/Windows microphone behavior
• adds regression coverage for input fallback, WebGL player settings, and reparse-point-safe output cleanup
• records the pre-challenge baseline, challenge-period work, public candidate URL, and remaining submission gates

Why

Unity WebGL does not expose the legacy UnityEngine.Microphone API used by the existing game, which initially produced 21 WebGL compiler errors. Browser completion also cannot depend on microphone permission. The contest branch therefore keeps native microphone play while providing a permission-independent keyboard route for WebGL.

Candidate build

• Public URL: https://home-protector-openaigame2026.vercel.app
• Generated output: 17 files, 44,955,417 bytes (42.87 MiB)
• Generated WebGL output remains ignored and is not committed to source history

Verification

• PASS unity-editmode total=23 passed=23 failed=0
• PASS unity-validate
• PASS unity-playmode total=3 passed=3 failed=0
• PASS unity-buildwebgl
• build log marker: HOME_PROTECTOR_WEBGL_BUILD_OK ... scenes=2 bytes=44955417
• PASS unity-repo-hygiene files=2480 assets=2428 manifest=125
• public index, loader, data, framework, and Wasm resources return HTTP 200 with expected MIME types
• independent review found no P0 issues

Remaining release gates

• manually complete Loading → gameplay → final result in a fresh browser session
• expose Evening: F, then click a position in the game or approved hosting shell
• capture the required thumbnail and approve the final title/≤200-character introduction

Scope boundaries

• no generated WebGL build output in the source branch
• no in-game AI director
• no rewrite of the legacy combat engine
• no unrelated Windows-release work before the qualifier cutoff