WASM plugin extensions

[jahvon]

Implement a WebAssembly-based plugin system that enables extending flow with custom functionality in two key areas: executable template generation and programmable executable runtime. This would allow developers to create plugins in any WASM-compatible language.

Plugin Types

1. Template Generator Plugins

Plugins that generate flow executables from external sources or formats.

# Plugin registration
plugins:
  - name: taskfile-converter
    type: template-generator
    wasm: plugins/taskfile.wasm

2. Runtime Executor Plugins

Plugins that implement new executable types with custom runtime behavior.

# Plugin registration
plugins:
  - name: custom-runtime
    type: runner
    wasm: plugins/custom-executor.wasm