feat: add basic TinyGo compat

[pancsta]

This PR adds TinyGo compatibility via codegen behind -tags=tinygo.

/pkg/machine seems to work well, but the lack of networking for WASI is a blocker for /pkg/rpc. Once solved, the serialization has to switch to andreyvit/tinyjson, with /pkg/rpc.(*Server) being able to handle both encodings within the same build tag.

Changes:

• build tag split into *.big.go and *.tiny.go
• codegen for schemas, handlers, and args
• Machine.BindHandlerMaps(...)
• v3 schema format

# /examples/tinygo
$ env GOTOOLCHAIN=go1.25.8 tinygo test -v ./
=== RUN   TestFileProcessing
    [state] +DownloadingFile
    [exter] Downloading file... 
    waiting: DownloadingFile to FileUploaded
    [state] +FileDownloaded -DownloadingFile
    [auto_] +ProcessingFile
    [exter] processFileActivity succeed /tmp/temporal_sample46331932
    [state] +FileProcessed -ProcessingFile
    [exter] cleanup /tmp/temporal_sample121180902
    [auto_] +UploadingFile
    [exter] uploadFileActivity begin /tmp/temporal_sample46331932
    [exter] uploadFileActivity succeed /tmp/temporal_sample46331932
    [state] +FileUploaded -UploadingFile
    [exter] cleanup /tmp/temporal_sample46331932
    (FileDownloaded:1 FileProcessed:1 FileUploaded:1)
    (FileDownloaded:1 FileProcessed:1 FileUploaded:1) [Exception:0 DownloadingFile:2 ProcessingFile:2 UploadingFile:2]
    
        0 Exception
            |Tick     0
        0 DownloadingFile
            |Tick     2
            |Remove   FileDownloaded
        1 FileDownloaded
            |Tick     1
            |Remove   DownloadingFile
        0 ProcessingFile
            |Tick     2
            |Auto     true
            |Require  FileDownloaded
            |Remove   FileProcessed
        1 FileProcessed
            |Tick     1
            |Remove   ProcessingFile
        0 UploadingFile
            |Tick     2
            |Auto     true
            |Require  FileProcessed
            |Remove   FileUploaded
        1 FileUploaded
            |Tick     1
            |Remove   UploadingFile
        
--- PASS: TestFileProcessing (0.20s)
PASS
ok      github.com/pancsta/asyncmachine-go/examples/tinygo      0.204s

TLDR; TinyGo is not Go