fix: pin frontend dev server heap ceiling (#91)

[AntoineToussaint]

Closes #91.

Summary

• The nextjs service agent starts the frontend with npm run dev (run logs: > npm run prepare:frontend && next dev -p <port>), so the dev process inherits Node's ~2 GB old-space default — the OOM GC lines show it dying at a ~2048 MB ceiling (1944.0 (2060.0) MB), well below the 4288 MB the same Node reports unconstrained. Nothing in the repo sets a limit, so under Turbopack + reactCompiler + transpiled plugin workspaces the dev compiler grows past that ceiling and OOMs within minutes, taking the port with it and reading as an unreachable site after a successful start.
• Root cause is the inherited ceiling, not a repo-set cap: the dev script is the one in-repo layer the agent runs, so pinning an explicit --max-old-space-size=8192 there makes the ceiling asserted rather than inherited by every consumer following the documented dogfood command — instead of an invisible NODE_OPTIONS on each person's shell.
• Scope kept tight: reactCompiler and transpilePackages are deliberate (plugin HMR, product decision); reducing them would regress behavior, so this only lifts the ceiling.

Test plan

• node --test module/tools/base-integrity.test.mjs — 20/20 pass, including "the committed canonical manifest matches the tree it ships with" (manifest regenerated via base-integrity.mjs gen for the edited base package.json + new test file).
• New scripts/dev-heap-ceiling.test.mjs (vitest pure project) asserts the dev script pins an explicit old-space ceiling above the inherited 2048 MB default and applies it to next dev. Verified the assertions pass against the real package.json (deps not installed in this worktree, so validated with plain Node rather than a full npm ci).

Notes for the reviewer

• The issue's testing surface asks for a 10-minute idle HTTP soak. That can't live in CI, so the committed test instead mechanically prevents regression to the inherited ~2 GB ceiling. A live soak against codefly run service --env local-dogfood is the manual confirmation.
• 8192 is a generous headroom ceiling (matches the value that was already stabilizing runs), not a tuned minimum — --max-old-space-size is a cap, not a reservation.

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