fix(recipes): build deploy against .env_prod; harden image save

Recipe image upload failed in prod with ENOENT writing the full image.
Root cause: the deploy built against the dev .env, whose relative
IMAGE_DIR="./imgs/" resolves under the service's dist/ working dir
instead of the real served image directory — and `$env/static/private`
is inlined at build time, so dev values shipped to prod.

- deploy.sh: source .env_prod (overridable via PROD_ENV) into the env
  before `pnpm build`, so prod values win over .env for the whole build
  lifecycle; abort if it's missing rather than ship a dev-env build.
- .gitignore: ignore .env_* so .env_prod (prod secrets) isn't committed
  (the existing .env.* dot pattern didn't match the underscore form).
- imageProcessing: mkdir -p the full/thumb dirs before writing. The
  WebP passthrough writes the full image with fs.writeFile, which (unlike
  sharp's toFile) does not create parent dirs.
- recipeFormHelpers: add serializableFormValues() and use it in the add/
  edit actions' fail() returns. Returning raw formData (now containing the
  recipe_image File) crashed the action response with a non-POJO devalue
  error, masking the real failure with an opaque 500.

.gitignore

@@ -7,6 +7,7 @@ node_modules
 /package
 .env
 .env.*
+.env_*
 !.env.example
 vite.config.js.timestamp-*
 vite.config.ts.timestamp-*