build: export compile_commands.json from the base preset (#67)

Add CMAKE_EXPORT_COMPILE_COMMANDS=ON to the hidden base configure preset so every
preset emits build/<preset>/compile_commands.json — making `just lint`
(run-clang-tidy) work out of the box. Build-dir only; no effect on compiled output.

Author: CameronBrooks11

CMakePresets.json

@@ -12,6 +12,7 @@
       "generator": "Ninja",
       "binaryDir": "${sourceDir}/build/${presetName}",
       "cacheVariables": {
+        "CMAKE_EXPORT_COMPILE_COMMANDS": "ON",
         "CMAKE_BUILD_TYPE": "Release",
         "CMAKE_TOOLCHAIN_FILE": "$env{VCPKG_ROOT}/scripts/buildsystems/vcpkg.cmake",
         "FLUXGRAPH_BUILD_TESTS": "ON",