feat: add Devnet frontend package foundations

[schickling-assistant]

Problem

Devnet needs one exact pnpm runtime across composed repositories and an exact Storybook listener port. Storybook 10.6 passes its selected port only to Vite HMR, so the HTTP listener can still choose another port and cannot participate in socket-ownership readiness.

Goal

Provide the canonical pnpm 12.4.1 runtime and a single reusable downstream patch authority that makes Storybook's Vite HTTP listener use options.port while retaining Storybook's HMR server.

Decisions

• Keep the Storybook patch in @overeng/utils and export the same registry object to the workspace and downstream consumers. This avoids two patch authorities.
• Match the exact Storybook 10.6 bundle source and require exactly one replacement in the test. Upstream drift therefore fails closed.
• Set pnpm 12 pnpm_config_pm_on_fail=ignore in the Nix wrapper. The wrapper already supplies the exact authoritative pnpm, so runtime self-download would duplicate authority and fail in Nix sandboxes.

Verification

• CI=1 packages/@overeng/utils/node_modules/.bin/vitest run packages/@overeng/utils/src/node/storybook/builder-vite-patch.unit.test.ts — 1 file and 1 test passed.
• Built flake.lib.mkPnpm with Nix, then ran its pnpm --version from a fresh home with registry proxies pointed at a closed local port — exit 0, 12.4.1, no stderr.
• pnpm install --frozen-lockfile completed with the committed lockfile unchanged.
• The branch-owned lint:fix:format changed only completion-reporter.ts; .devenv/profile/bin/oxfmt --check passes that file.
• git diff --check passed.

Pre-flip deviation: devenv tasks run check:quick is blocked before project checks by mr:setup, which rejects this legacy flat composition worktree. Creating a replacement worktree also failed under schickling/dotfiles#2954. Johannes approved committing the formatter-only repair with the exact local checks above and requiring full PR CI before merge.

Complexity

No new runtime dependency. The patch registry and exact-bundle test are the minimum compatibility boundary until Storybook ships the listener-port fix.

Concerns

The patch intentionally fails when Storybook changes the targeted bundle. A Storybook update must refresh or remove the patch with source-level verification.

Friction & bottlenecks

• Megarepo composition incident schickling/dotfiles#2954 prevents the mandatory aggregate quick check in both the existing and newly requested validation worktrees.
• gh-ci-utils logs currently fails its GitHub App token request with an administrative 403; raw GitHub logs were used under the documented exit-4 fallback.

Follow-ups

• Remove the Storybook patch after the equivalent upstream fix is released and adopted.
• Re-run check:quick after schickling/dotfiles#2954 clears.

References

• Refs schickling/dotfiles#2954

Posted on behalf of @schickling

field	value
agent_identity	dev3.direct.omp.dezb8g5k
session	unknown
agent_persona	generalist
agent_supervisor	unavailable
agent_tool	OMP
agent_tool_version	18.2.6
agent_runtime	OMP 18.2.6
agent_model	openai-codex/gpt-5.6-sol
worktree	unknown
tooling_profile	dotfiles@965ef7e-dirty