fix(project): robust project file loading (A5, C6)

[Vadim1987]

A5: codeload crashed on non-string input (readfile can yield nil content on read race / missing read / SD eject); guard and return an error instead of loadstring(nil). C6: ProjectService:run discarded the readfile success flag, so a missing main.lua compiled the error message as code; check the flag and return the real message.

[Copilot]

Pull request overview

This PR hardens Lua project file loading to avoid crashes and misleading compilation errors when project source cannot be read (e.g., missing main.lua or transient read failures).

Changes:

• Add a defensive guard in codeload to avoid calling loadstring with non-string input.
• Fix ProjectService:run to respect readfile’s success flag and return the real read error instead of compiling the error message as code.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 2 comments.

File	Description
src/util/lua.lua	Adds a type guard before loadstring to prevent crashes on nil/non-string code.
src/model/project/project.lua	Checks readfile’s success flag in ProjectService:run to propagate missing/failed read errors correctly.

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[dsent]

The extra changes suggested by Copilot seem overdefensive and unnecessary to me. I think we should ignore them. If everyone agrees, I will reject-resolve.

[dsent]

@aldum pls confirm