tools/breenix-runs: `swift build -c release` crashes the Swift 6.3.3 CopyPropagation SIL pass on RunShow.renderSubsystems - make app ships a debug build

[ryanbreen]

The swift build -c release command crashes the Swift 6.3.3 CopyPropagation SIL pass when building RunShow.renderSubsystems.

Details:

• Toolchain: Xcode 26.6, Swift 6.3.3
• Function affected: RunShow.renderSubsystems
• Reference: DESIGN.md 2.4

Request: Restructure the function so that release builds succeed. Additionally, make app should ship a release build. Optionally create a separate debug target for development.

Consider reporting this upstream to the Swift compiler team if it's a genuine compiler bug.

[ryanbreen]

Landed at d41d8f3 (PR #876, merging #875 into main).

[ryanbreen]

PR #876 restructures renderSubsystems, make app ships release, make app-debug added; landing re-smoke green.