C stock example

A multi-package pure C app. It has a stock CLI, a store library that reads JSON through cJSON, a generated store_build.h header and a packaged stock.json.

bazel build //examples/c-app/...
bazel test //examples/c-app/...
bazel run //examples/c-app/cli:stock -- total
bazel run //examples/c-app/cli:stock -- get bolt-m6
bazel run //examples/c-app/cli:stock -- --file path/to/stock.json list

Without --file or STOCK_FILE, stock reads the packaged stock.json through runfiles, so the binary runs from any directory. Relative --file paths resolve against the directory you ran bazel run from. Quantities and prices must be whole numbers from 0 to 1000000.

Exit codes: 0 ok, 2 usage, 3 unreadable or malformed stock file, 4 unknown item. exit_codes_test runs the binary through each code.

Sources build as C11 with -std=c11. store_test and cli_test are C programs and fail to compile as C++. linkage_test includes the same header from C++ and links the C library. cJSON is a pinned http_archive declared in MODULE.bazel. format_test checks the sources against the repository .clang-format.

diagnostics_test compiles and lints files with a syntax error, a type error and a lint finding, and expects each to fail.

Another workspace builds, tests, runs and copies both apps with bazel test //cc/tests/consumer:app_consumer_test.