generateAll discovered modules by scanning the workspace for legacy
dagger.json files with sdk.source "python". cli-1.0 workspace modules use
dagger-module.toml and are tracked in [[modules.<sdk>.as-sdk.modules]], so
that scan finds nothing and generate-all returns an empty changeset.

Discover managed modules from the engine's source of truth instead, via
currentModule.asSDK.modules.

Signed-off-by: Yves Brissaud <yves@dagger.io>

Problem:
generateAll now reads currentModule.asSDK.modules. That field is part of the
CLI 1.0 schema view, so this SDK module has to load with a v1 engine contract.
Leaving the module on the v0.21 schema makes the new discovery path fail before
the generator logic can run.

Change:
- set engineVersion to v1.0.0-0
- pin polyfill to the sdk-sdk commit that handles dagger-module.toml
- update Dang field projections to the v1 syntax

This does not change what generated Python modules contain. It makes the SDK
helper module load against the schema it now uses.

Signed-off-by: Guillaume de Rouville <guillaume@dagger.io>

Problem:
The e2e workspace only loaded the e2e module. That was enough while generateAll
scanned dagger.json files, but it no longer matches the CLI 1.0 contract.
generateAll now reads currentModule.asSDK.modules, which only exists when the
SDK module is installed in the workspace with an as-sdk entry.

Change:
Install the local Python SDK module in dagger.toml and list the fixture modules
it manages. That makes the e2e workspace look like the user-facing flow after
`dagger sdk install python`: the SDK owns a set of modules recorded under
[[modules.python-sdk.as-sdk.modules]].

The SDK root also exposes @generate functions. Unqualified `dagger check` treats
those generators as checks and would fail because python-sdk:generate-all
produces fixture changes. Add check.skip = ["*"] on the SDK root entry so the
repo's default check runs the e2e checks without treating the SDK helper's own
generators as repo checks. The e2e module still calls generateAll directly, so
coverage for the new discovery path remains.

Signed-off-by: Guillaume de Rouville <guillaume@dagger.io>