Port envd from e2b with internalized shared packages and Connect RPC

- Copy envd source from e2b-dev/infra, internalize shared dependencies
  into envd/internal/shared/ (keys, filesystem, id, smap, utils)
- Switch from gRPC to Connect RPC for all envd services
- Update module paths to git.omukk.dev/wrenn/{sandbox,sandbox/envd}
- Add proto specs (process, filesystem) with buf-based code generation
- Implement full envd: process exec, filesystem ops, port forwarding,
  cgroup management, MMDS integration, and HTTP API
- Update main module dependencies (firecracker SDK, pgx, goose, etc.)
- Remove placeholder .gitkeep files replaced by real implementations

envd/go.mod

@@ -1,9 +1,42 @@
-module github.com/wrenn-dev/envd
+module git.omukk.dev/wrenn/sandbox/envd
 
-go 1.23.0
+go 1.25.5
 
 require (
-	github.com/mdlayher/vsock v1.2.1
-	google.golang.org/grpc v1.71.0
-	google.golang.org/protobuf v1.36.5
+	connectrpc.com/authn v0.1.0
+	connectrpc.com/connect v1.19.1
+	connectrpc.com/cors v0.1.0
+	github.com/awnumar/memguard v0.23.0
+	github.com/creack/pty v1.1.24
+	github.com/dchest/uniuri v1.2.0
+	github.com/e2b-dev/fsnotify v0.0.1
+	github.com/go-chi/chi/v5 v5.2.5
+	github.com/google/uuid v1.6.0
+	github.com/oapi-codegen/runtime v1.2.0
+	github.com/orcaman/concurrent-map/v2 v2.0.1
+	github.com/rs/cors v1.11.1
+	github.com/rs/zerolog v1.34.0
+	github.com/shirou/gopsutil/v4 v4.26.2
+	github.com/stretchr/testify v1.11.1
+	github.com/txn2/txeh v1.8.0
+	golang.org/x/sys v0.42.0
+	google.golang.org/protobuf v1.36.11
+)
+
+require (
+	github.com/apapsch/go-jsonmerge/v2 v2.0.0 // indirect
+	github.com/awnumar/memcall v0.4.0 // indirect
+	github.com/davecgh/go-spew v1.1.1 // indirect
+	github.com/ebitengine/purego v0.10.0 // indirect
+	github.com/go-ole/go-ole v1.2.6 // indirect
+	github.com/lufia/plan9stats v0.0.0-20211012122336-39d0f177ccd0 // indirect
+	github.com/mattn/go-colorable v0.1.13 // indirect
+	github.com/mattn/go-isatty v0.0.20 // indirect
+	github.com/pmezard/go-difflib v1.0.0 // indirect
+	github.com/power-devops/perfstat v0.0.0-20240221224432-82ca36839d55 // indirect
+	github.com/tklauser/go-sysconf v0.3.16 // indirect
+	github.com/tklauser/numcpus v0.11.0 // indirect
+	github.com/yusufpapurcu/wmi v1.2.4 // indirect
+	golang.org/x/crypto v0.41.0 // indirect
+	gopkg.in/yaml.v3 v3.0.1 // indirect
 )