chore: OSS公開に向けたドキュメント・CI整備

[rinngo0302]

🔗 Issue

なし（OSS公開準備タスク）

📚 Description

EasyGLをOSSとして公開するためのドキュメント・テンプレート・コード整備を行いました。

• CONTRIBUTING.md を追加（貢献ガイド、コーディング規約、コミットメッセージ規約）
• README.md にCI / License / C++17 / Header-only バッジを追加
• Issue テンプレート を追加（.github/ISSUE_TEMPLATE/01-default.yml）
• PR テンプレート を追加（.github/PULL_REQUEST_TEMPLATE.md）
• src/ のコードフォーマット を統一

🚧 Not included in this PR

• CMakeLists.txt の再整備（add_subdirectory / find_package 対応）
• バージョンタグの付与
• examples/ ディレクトリの追加
• CHANGELOG.md の追加

📝 Reviewer checklist & Notes

ドキュメントとテンプレートの追加が中心なので、機能への影響はありません。

Summary by CodeRabbit

• New Features

  • Per-light shader support for multi-light rendering
  • Initialization now returns success/failure

• Documentation

  • Comprehensive API reference, CONTRIBUTING guide, and expanded README
  • GitHub issue and PR templates added

• Chores

  • Packaging/install support via CMake added
  • Standardized .gitignore and repository-wide formatting

• Tests / CI

  • Test build workflow updated and new CI build step for native compilation

[coderabbitai]

📝 Walkthrough

Walkthrough

Reworks build to a packagable CMake INTERFACE target with install/export/config; adds GitHub issue/PR templates and CI step; large docs and contributing additions; widespread code formatting; API change: EZ_Init now returns bool; shader struct gains per-light uniform location arrays; lights get default ambient/specular values.

Changes

Cohort / File(s)	Summary
GitHub templates & CI .github/ISSUE_TEMPLATE/01-default.yml, .github/PULL_REQUEST_TEMPLATE.md, .github/workflows/ci.yml	Adds default issue and Japanese PR templates; CI workflow renames a build step and adds a separate "Build (g++)" compilation of the test executable.
CMake packaging & test wiring CMakeLists.txt, cmake/EasyGLConfig.cmake.in, CMakeFiles/CMakeSystem.cmake, test/CMakeLists.txt	Converts project to an installable EasyGL::EasyGL INTERFACE target, adds package/config/version generation, CPack-friendly pieces, version 0.1.0, EASYGL_BUILD_TESTS toggle, and conditional test target wiring for parent vs standalone builds.
Documentation & repo metadata README.md, CONTRIBUTING.md, docs/api-reference.md, .gitignore	Adds comprehensive README, CONTRIBUTING, large API reference, and standardizes .gitignore entries.
Public API & tests src/EasyGL.hpp, test/test_ez.cpp, test/*	Public API change: EZ_Init now returns bool (call sites updated to check result); test include path and startup error handling adjusted; minor test behavior tweak (object delta).
Shader subsystem src/shader/EZ_Shader.hpp, src/shader/EZ_Shader.cpp	Adds per-light uniform location arrays (light_position_loc, light_color_loc, light_ambient_loc, light_specular_loc) to _EZ_Shader; implementation files largely reformatted.
Light defaults src/light/EZ_Light.cpp, src/light/EZ_Light.hpp	Initializes ambient_strength = 0.3f and specular_strength = 0.5f in EZ_CreateLight; plus formatting updates.
2D subsystem src/2d/EZ_2d.cpp, src/2d/EZ_2d.h, src/2d/font/*, src/2d/image/*	Adds forward decl for _EZ_2D_DestroyFreeType, ensures shader compile failure returns 0 early, and applies broad formatting/brace-style normalization across font and image modules.
Core source formatting & minor behavior src/* (EasyGL.cpp/hpp, camera, mesh, model, object, texture, shader, texture headers)	Widespread stylistic changes (brace placement, spacing, casts); small functional tweaks: added logging on object creation, some default initializations, and a few immediate-return error paths.
Packaging/test support & CI assets test/*, root CMakeLists.txt	Adds packaging helpers, writes package config/version files, and updates post-build asset copying for the test executable.

Estimated code review effort

🎯 4 (Complex) | ⏱️ ~50 minutes

Poem

🐇 I hopped through CMake and tidied every trail,
New templates flutter, docs tell the tale,
Lights wake with a gentle ambient grin,
Shaders now count each lamp tucked within,
EZ_Init returns true — the demo can begin. ✨

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Note

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