feat(components): add signed runtime components across bindings

[Goldziher]

Summary

• add first-class component contracts and feature-profiled component builds to Alef configuration and code generation
• add a stable C ABI crate plus a runtime for signed manifest verification, content-addressed caching, dynamic loading, and typed contract tables
• add alef component build, package, verify, and lock workflows for CI-produced artifacts
• expose component load, prefetch, status, and cache-path APIs across Alef's native bindings
• emit explicit unsupported errors for WebAssembly and mobile targets where downloaded executable code is outside the v1 support policy

Security and distribution

• CI retains the Ed25519 private signing key
• generated binding packages contain crate-scoped lock data with trusted public keys and exact artifact metadata
• downloads are size- and SHA-256-pinned, signature-verified, protected against archive traversal, and atomically installed into a content-addressed cache
• dynamic libraries remain pinned while component handles and contract tables are in use

Binding coverage

• direct native runtime: Python, Node.js, Ruby, PHP, Elixir, R, Dart/FRB, and Swift
• shared C manager ABI: C, Go, Java/Panama, Kotlin/JVM, C#, Zig, and Dart/FFI
• Rustler-backed: Gleam
• explicit v1 unsupported surfaces: WebAssembly, Kotlin Android, Android JNI, and Apple mobile

Validation

• cargo test --workspace
• cargo test component --lib (60 passed)
• task lint
• cargo fmt --all -- --check
• git diff --check
• generated C host smoke test against a real signed component: download, verification, cache, load, status, and prefetch all succeeded

[Goldziher]

Review status: not mergeable in its current form. This draft conflicts with current main and predates the 0.60.2 binding-safety, ownership, failure-atomicity, naming, Jinja, and file-modularization changes. Please rebase the feature branch onto current main after the 0.60.2 stabilization lands, resolve the root-flat crate architecture question, regenerate the schema through the version workflow, and rerun the full binding/component security matrix. I am leaving it as a draft rather than merging an 8,136-line conflicted change into the active release branch.