Frontend extension fallback

Two declarations expose a pack's browser-side directory, and both write into one registry keyed by name: module-level WEB_DIRECTORY in the pack's __init__.py, keyed by the pack's directory name, and [tool.comfy].web in pyproject.toml, keyed by project.name. Either is honored only when the directory exists on disk; a wrong relative path is skipped with no error, so "my script never loads" is usually a path. [tool.comfy].web also requires that the runtime can read pyproject.toml and is skipped with only a log warning otherwise, so WEB_DIRECTORY has fewer preconditions.

Declare one. Declaring both resolves by name rather than merging: equal names — the common case — mean WEB_DIRECTORY applies second and silently drops the pyproject.toml entry; differing names serve both prefixes and the second registration of one name raises.

Files are served at /extensions/<name>/…, and the listing the frontend loads enumerates **/*.js only, so build TypeScript or JSX to .js. An extension's name must be unique; registering it twice raises.

Treat frontend state as presentation only. Every non-secret value the Python node reads must live in the persisted widget value, because the browser layer is absent for an API-submitted prompt. Never put credentials in widget values — read secrets from the environment or the runtime's secret mechanism.