feat: add code quality toolchain

Three Pillars

1. Static Analysis (clang-tidy + compiler warnings)

Layer	Trigger	Config
Editor (real-time)	clangd auto	.clangd
CLI (per-file)	clang-tidy file.cpp	.clang-tidy
Build (all TUs)	CEPCSW_STRICT=ON	CMakeLists.txt → CMAKE_CXX_CLANG_TIDY
CI (full build + test)	build:strict job (manual)	.gitlab-ci.yml

Compiler baseline: -Wall -Wextra -Wpedantic -Wshadow. Strict mode adds -Werror.

2. Formatting (clang-format)

Layer	Trigger	Policy
Editor (save)	clangd auto	.clang-format
CLI	clang-format -i --style=file	.clang-format
Pre-commit	source setup.sh (auto)	new files → strict reject; old files → auto-format
CI	format-check job (automatic)	new files in MR → strict check; old files → skip

3. Dynamic Analysis (ASan + UBSan)

Layer	Trigger
Local build	CEPCSW_STRICT=ON ./build.sh
CI	build:strict job (manual) — build + test with sanitizers

---

Quick Start

# Daily build
source setup.sh && ./build.sh

# LSP (editor)
CEPCSW_BEAR=ON ./build.sh              # → compile_commands.json

# Strict mode (all three pillars)
CEPCSW_STRICT=ON ./build.sh            # -Werror + clang-tidy + ASan + UBSan

Old Code Compatibility

Cutoff date: 2026-05-01 (CEPCSW_STRICT_CUTOFF). Files last modified before this date are exempt from strict checks. Pre-commit auto-formats old files; CI skips them.

Design Principles

• One switch: CEPCSW_STRICT=ON enables all three pillars
• Zero pip/npm: all tooling from CVMFS
• Pure bash: no external dependencies for hooks
• Incremental: old code exempt, new code strict

Files (16)

.clang-format .clang-tidy .clangd .vscode/ .dir-locals.el CMakeLists.txt cmake/CEPCSWOptions.cmake cmake/CEPCSWStrictWarnings.cmake build.sh setup.sh scripts/git-hooks/pre-commit .gitlab-ci.yml AGENTS.md doc/editors-setup.md