build(repo): generate the site's route tree before mutation testing

[systemfsoftware-maker]

After #73 the Release gate's dry run passes. The TypeScript checker's first compile then failed (run 37709038743, job "mutation · @endgame/site"):

src/router.tsx(5,27): error TS2307: Cannot find module './routeTree.gen' or its corresponding type declarations.
src/routes/guestbook.tsx(5,38): error TS2345: Argument of type '"/guestbook"' is not assignable to parameter of type 'undefined'.
src/routes/index.tsx(7,38): error TS2345: Argument of type '"/"' is not assignable to parameter of type 'undefined'.

This makes the mutation task generate the route tree first, the same way typecheck does.

Cause

• apps/site/src/routeTree.gen.ts is generated by TanStack Router and git-ignored (.gitignore:15). The site's generate script (tsr generate) writes it. Turbo's generate task declares it as its output (turbo.json:16-26).
• CI's typecheck leg runs pnpm typecheck. In turbo, typecheck depends on generate (turbo.json:52-55), so the file exists before tsc runs. The site's own typecheck script also starts with tsr generate.
• The Release gate runs turbo run mutation --filter=<package> (release-gate.yml:59). mutation depended only on ^build (turbo.json:107-109), so nothing wrote the route tree. Stryker's checker compiles the package's tsconfig.json, which includes src.

Change

turbo.json: the mutation task depends on generate as well as ^build. That's the same edge typecheck has. Nothing else changes: no generated file is committed, there's no new tool, the checker stays on, the mutate globs are unchanged, and break stays at 100.

Proof

--dryRunOnly stops before the checker's compile. In a checkout with no route tree it exits 0 and the log ends at phase mutation-test. So the proof shows the task graph, then the compile itself.

Bootstrapped worktree at f8f60c3, Linux, sandboxed, starting with no apps/site/src/routeTree.gen.ts:

$ cd apps/site && tsc -p tsconfig.json --noEmit     # no route tree: exit 1
src/router.tsx(5,27): error TS2307: Cannot find module './routeTree.gen' ...
src/routes/guestbook.tsx(5,38): error TS2345: ... '"/guestbook"' ... 'undefined'.
src/routes/index.tsx(7,38): error TS2345: ... '"/"' ... 'undefined'.

$ turbo run mutation --filter=@endgame/site --dry=json
{"taskId":"@endgame/site#mutation","dependencies":["@endgame/site#generate"]}
{"taskId":"@endgame/site#generate","command":"tsr generate","outputs":["src/routeTree.gen.ts"]}

$ turbo run mutation --filter=@endgame/site          # exit 2: the main-CI guard refuses, after generate ran
@endgame/site:generate: $ tsr generate
@endgame/site:mutation: $ stryker run
@endgame/site:mutation: exit 2 (ConfigError): mutation runs only on main CI — run mutation testing on main CI (GitHub Actions)
# apps/site/src/routeTree.gen.ts now exists

$ cd apps/site && stryker run --dryRunOnly --cleanTempDir false   # exit 0
# the kept sandbox contains src/routeTree.gen.ts

The checker compiles that sandbox. The two mutated files in the kept sandbox hold Stryker's instrumented code, so I put the original two files back in place of the instrumented copies before compiling. That gives the sandbox before any mutant:

• tsc -p tsconfig.json --noEmit in the sandbox exits 0 with no output.
• Moving src/routeTree.gen.ts out of the sandbox brings back the same three errors as CI.

Also run on this head: pnpm check:ci exits 0. All 25 @systemfsoftware/* packages resolve from our flakes, 9/9 tasks pass, and dist and the sandbox proofs pass.

Mutants weren't run, because the engine's guard allows that only on main CI. Done means the next Release gate on main produces the @endgame/site report at break 100.

Conductor ruling, cycle 109.

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[kiro-systemf]

Verified: 9/9 green on f8f60c3, one turbo dependsOn edge, sandbox compile exit 0 with route tree, 0 threads, hunt clean.