feat: make PHP module discovery cwd-aware

[tiborvass]

What changed

• Replace workspace-root dagger.json scanning with cwd-aware config discovery through dagger/polyfill.
• Support both CLI 1.0 dagger-module.toml and legacy dagger.json, choosing the nearest config regardless of filename ordering.
• Intersect discovered roots with the PHP SDK modules managed by the explicitly passed workspace via currentModule.asSDK(workspace: ws).
• Separate stable workspace-root-relative Mod.rootPath from the cwd-relative public Mod.path.
• Anchor rootPath at / when resolving module sources so generation works from a module root or another nested directory.
• Exclude Composer vendor trees, update the polyfill dependency, and document the new behavior.
• Add end-to-end fixtures for mixed config formats, managed/non-PHP filtering, explicit workspace resolution, cwd scoping, and rooted generation.

Why

The previous implementation scanned every legacy dagger.json from the workspace root. That ignored the caller's cwd, could not discover modern TOML modules, and could disagree with the workspace's engine-owned managed-module list.

Keeping root-relative identity separate from cwd-relative display paths also prevents nested generation from interpreting a stable module root relative to the cwd and prefixing that cwd twice.

Validation

Validated against a current locally built Dagger dev engine:

dagger check

All 3 checks pass:

• e-2-e:module-lookup-check
• e-2-e:module-discovery-check
• e-2-e:generate-cwd-check

Related implementations

• feat: make Python module discovery cwd-aware python-sdk#9
• Make module discovery cwd-aware and resolve dagger-module.toml java-sdk#8
• fix: root cwd-aware generation paths java-sdk#9
• explicitly pass workspace to currentModule.asSDK typescript-sdk#13

[TomChv]

Let's do dagger/typescript-sdk#12 (modulesource.generateLocalDependencies changes) in a follow up PR, this one module looks pretty good already

[TomChv]

Trying to run dagger generate after initializing a php module throw this error:

loading module "/private/tmp/_manual_dagger_test/_test_php/.dagger/modules/bar": resolving module source "/private/tmp/_manual_dagger_test/_test_php/.dagger/modules/bar": failed to load sdk for local module source: invalid SDK: "github.com/dagger/dagger/sdk/[email protected]"

The fix is to pin engineVersion to v1.0.0-beta.7 instead of latest until we fix that behaviour in the engine?