Fix dev-build.sh clobbering Datadog's SPM_BUILD flag

[alexkroman]

Problem

scripts/dev-build.sh failed to build locally with:

cannot find type 'UIApplicationNotificationCallback' in scope
cannot find type '__dd_private_AppLaunchHandler' in scope
cannot find '__dd_private_ObjcExceptionHandler' in scope

…even though CI (check.sh) was green on the same dd-sdk-ios revision, Xcode, and Swift toolchain.

Root cause

dev-build.sh passed SWIFT_ACTIVE_COMPILATION_CONDITIONS=DEBUG on the xcodebuild command line to strip UITEST_HOOKS from a clean local build. A command-line build-setting override applies to every target in the graph — including SwiftPM dependencies — and replaces (not appends to) their value.

dd-sdk-ios's Package.swift compiles DatadogCore/DatadogCrashReporting with .define("SPM_BUILD"). The global override wiped that out, so this guard went false:

#if SPM_BUILD
    internal import DatadogPrivate   // the ObjC module with the missing symbols
#endif

Why CI didn't catch it: check.sh's xcodebuild never passes that override, so the dependency kept SPM_BUILD. dev-build.sh is local-only, and Datadog (#8) was the first dependency to rely on a custom compilation condition — so a long-standing override in dev-build.sh only just started breaking builds.

Fix

• Add a Debug-Local build configuration (debug type, UITEST_HOOKS off) in project.yml.
• dev-build.sh selects it with -configuration Debug-Local instead of overriding the global setting — a per-config setting only touches the app target, so SwiftPM dependencies keep their own flags.
• The "Install to /Applications" postBuildScript now installs for Debug-Local as well as Debug.
• Regenerated project.pbxproj via xcodegen (keeps the drift gate green).

Verification

• Full app build with -configuration Debug-Local → BUILD SUCCEEDED, with -DSPM_BUILD present on the DatadogCore compile.
• Debug-Local → SWIFT_ACTIVE_COMPILATION_CONDITIONS = DEBUG (no UITEST_HOOKS); Debug → DEBUG UITEST_HOOKS.
• Generated scheme unchanged (run/test Debug, archive Release).

🤖 Generated with Claude Code