fix(cloudflare): support remote images and external Dockerfiles in LocalContainerProvider

[john-royal]

LocalContainerProvider only handled the Effect-native main variant, so a container declared with a remote image (or an external context/dockerfile) died under alchemy dev with "Container requires a main entrypoint". The live ContainerProvider supports all three image variants; the local provider now mirrors it:

// main        → bundle + build context (unchanged)
// image       → dev: { imageUri } — the local runtime `docker pull`s it
// dockerfile  → dev: { context, dockerfile } — built against the user's context

Each variant also produces a content hash (sha256Object of the image URI, or directory hash + Dockerfile content) so change detection works the same as the main path.

Adds a dev-mode test (LocalContainer.test.ts) that deploys the existing remote-image fixture under a separate stack name, pulls mendhak/http-https-echo, and round-trips a request through the DO into the container's TCP port.

[alchemy-version-bot]

Install the packages built from this commit:

alchemy

bun add alchemy@https://pkg.ing/alchemy/7bb149c

@alchemy.run/better-auth

bun add @alchemy.run/better-auth@https://pkg.ing/@alchemy.run/better-auth/7bb149c

@alchemy.run/pr-package

bun add @alchemy.run/pr-package@https://pkg.ing/@alchemy.run/pr-package/7bb149c