feat: add CI/CD workflows, clang-format, and clang-tidy

[melogtm]

Adds CI gate on PRs and a CD release pipeline on tag push.

What's included

CI (.github/workflows/ci.yml)

• Triggers on all PRs and pushes to main
• Two jobs on ubuntu-latest:
• build-and-test — runs ./run_tests.sh (configure + build + ctest)
• lint — clang-format --dry-run --Werror + clang-tidy against all source
• Any PR with build failure, test failure, or formatting violation is blocked

CD (.github/workflows/release.yml)

• Triggers on v*.. tag push
• Builds the shell in Release mode and attaches build/shell to a GitHub Release
  Tooling config
• .clang-format — LLVM-based, 4-space indent, 100-column limit, tuned to match existing code style
• .clang-tidy — scoped checks (bugprone, clang-analyzer, performance, portability, readability) with suppressions for noise irrelevant to a C11 codebase

Source changes

• All source files formatted with clang-format for a clean baseline (no CI violation on merge)
• pipeline.c: fixed math precedence parens and widening cast
• execute.c: removed dead store of glob_eligible
• README.md: added CI status badge

Verification

• clang-format --dry-run --Werror passes clean
• clang-tidy reports zero warnings
• All 5 test suites pass (100%)

#20

[Copilot]

Pull request overview

Adds CI/CD automation and C/C++ formatting/linting configuration to enforce consistent style and quality checks, along with repository-wide clang-format reformatting and a few small source/test cleanups.

Changes:

• Added GitHub Actions CI workflow for build/test and lint (clang-format + clang-tidy).
• Added GitHub Actions release workflow to publish a built shell artifact on semver tag pushes.
• Introduced .clang-format / .clang-tidy and reformatted existing C sources/tests to match.

Reviewed changes

Copilot reviewed 21 out of 24 changed files in this pull request and generated 6 comments.

Show a summary per file

File	Description
tests/test_pipeline.c	Formatting-only changes and include reordering in pipeline tests.
tests/test_input.c	Formatting-only changes to input-splitting tests and include ordering.
tests/test_glob.c	Formatting-only changes to glob expansion tests.
tests/test_framework.h	Reflowed assertion macros to match clang-format output.
tests/test_execute.c	Formatting-only changes and include reordering in execute tests.
tests/test_builtins.c	Formatting-only changes and minor readability reflow in builtins tests.
src/utils/utils.h	Formatting-only changes (spacing/wrapping).
src/utils/utils.c	Formatting-only changes (indentation/wrapping).
src/pipeline.c	Formatting and adjusted pipe FD allocation expression.
src/main.c	Formatting-only changes and include ordering.
src/input.c	Formatting-only changes and include ordering.
src/glob.c	Formatting-only changes and include ordering.
src/execute.c	Formatting and minor cleanup (removed unused local) in execute path.
src/builtins.c	Formatting-only changes and wrapping long initializer lines.
README.md	Added CI badge at top and reflowed content to match formatting baseline.
include/pipeline.h	Formatting-only changes.
include/input.h	Formatting-only changes.
include/glob_expand.h	Formatting-only changes.
include/execute.h	Formatting-only changes.
include/builtins.h	Formatting-only changes.
.github/workflows/release.yml	Added tag-triggered release workflow to build and attach build/shell.
.github/workflows/ci.yml	Added PR/push CI workflow with build/test and lint jobs.
.clang-tidy	Added clang-tidy checks configuration.
.clang-format	Added clang-format style configuration.

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