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/internal/shared/keys/key_test.go

@@ -0,0 +1,160 @@
+package keys
+
+import (
+	"fmt"
+	"strconv"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+)
+
+func TestMaskKey(t *testing.T) {
+	t.Parallel()
+	t.Run("succeeds: value longer than suffix length", func(t *testing.T) {
+		t.Parallel()
+		masked, err := MaskKey("test_", "1234567890")
+		require.NoError(t, err)
+		assert.Equal(t, "test_", masked.Prefix)
+		assert.Equal(t, "12", masked.MaskedValuePrefix)
+		assert.Equal(t, "7890", masked.MaskedValueSuffix)
+	})
+
+	t.Run("succeeds: empty prefix, value longer than suffix length", func(t *testing.T) {
+		t.Parallel()
+		masked, err := MaskKey("", "1234567890")
+		require.NoError(t, err)
+		assert.Empty(t, masked.Prefix)
+		assert.Equal(t, "12", masked.MaskedValuePrefix)
+		assert.Equal(t, "7890", masked.MaskedValueSuffix)
+	})
+
+	t.Run("error: value length less than suffix length", func(t *testing.T) {
+		t.Parallel()
+		_, err := MaskKey("test", "123")
+		require.Error(t, err)
+		assert.EqualError(t, err, fmt.Sprintf("mask value length is less than identifier suffix length (%d)", identifierValueSuffixLength))
+	})
+
+	t.Run("error: value length equals suffix length", func(t *testing.T) {
+		t.Parallel()
+		_, err := MaskKey("test", "1234")
+		require.Error(t, err)
+		assert.EqualError(t, err, fmt.Sprintf("mask value length is equal to identifier suffix length (%d), which would expose the entire identifier in the mask", identifierValueSuffixLength))
+	})
+}
+
+func TestGenerateKey(t *testing.T) {
+	t.Parallel()
+	keyLength := 40
+
+	t.Run("succeeds", func(t *testing.T) {
+		t.Parallel()
+		key, err := GenerateKey("test_")
+		require.NoError(t, err)
+		assert.Regexp(t, "^test_.*", key.PrefixedRawValue)
+		assert.Equal(t, "test_", key.Masked.Prefix)
+		assert.Equal(t, keyLength, key.Masked.ValueLength)
+		assert.Regexp(t, "^[0-9a-f]{"+strconv.Itoa(identifierValuePrefixLength)+"}$", key.Masked.MaskedValuePrefix)
+		assert.Regexp(t, "^[0-9a-f]{"+strconv.Itoa(identifierValueSuffixLength)+"}$", key.Masked.MaskedValueSuffix)
+		assert.Regexp(t, "^\\$sha256\\$.*", key.HashedValue)
+	})
+
+	t.Run("no prefix", func(t *testing.T) {
+		t.Parallel()
+		key, err := GenerateKey("")
+		require.NoError(t, err)
+		assert.Regexp(t, "^[0-9a-f]{"+strconv.Itoa(keyLength)+"}$", key.PrefixedRawValue)
+		assert.Empty(t, key.Masked.Prefix)
+		assert.Equal(t, keyLength, key.Masked.ValueLength)
+		assert.Regexp(t, "^[0-9a-f]{"+strconv.Itoa(identifierValuePrefixLength)+"}$", key.Masked.MaskedValuePrefix)
+		assert.Regexp(t, "^[0-9a-f]{"+strconv.Itoa(identifierValueSuffixLength)+"}$", key.Masked.MaskedValueSuffix)
+		assert.Regexp(t, "^\\$sha256\\$.*", key.HashedValue)
+	})
+}
+
+func TestGetMaskedIdentifierProperties(t *testing.T) {
+	t.Parallel()
+	type testCase struct {
+		name              string
+		prefix            string
+		value             string
+		expectedResult    MaskedIdentifier
+		expectedErrString string
+	}
+
+	testCases := []testCase{
+		// --- ERROR CASES (value's length <= identifierValueSuffixLength) ---
+		{
+			name:              "error: value length < suffix length (3 vs 4)",
+			prefix:            "pk_",
+			value:             "abc",
+			expectedResult:    MaskedIdentifier{},
+			expectedErrString: fmt.Sprintf("mask value length is less than identifier suffix length (%d)", identifierValueSuffixLength),
+		},
+		{
+			name:              "error: value length == suffix length (4 vs 4)",
+			prefix:            "sk_",
+			value:             "abcd",
+			expectedResult:    MaskedIdentifier{},
+			expectedErrString: fmt.Sprintf("mask value length is equal to identifier suffix length (%d), which would expose the entire identifier in the mask", identifierValueSuffixLength),
+		},
+		{
+			name:              "error: value length < suffix length (0 vs 4, empty value)",
+			prefix:            "err_",
+			value:             "",
+			expectedResult:    MaskedIdentifier{},
+			expectedErrString: fmt.Sprintf("mask value length is less than identifier suffix length (%d)", identifierValueSuffixLength),
+		},
+
+		// --- SUCCESS CASES (value's length > identifierValueSuffixLength) ---
+		{
+			name:   "success: value long (10), prefix val len fully used",
+			prefix: "pk_",
+			value:  "abcdefghij",
+			expectedResult: MaskedIdentifier{
+				Prefix:            "pk_",
+				ValueLength:       10,
+				MaskedValuePrefix: "ab",
+				MaskedValueSuffix: "ghij",
+			},
+		},
+		{
+			name:   "success: value medium (5), prefix val len truncated by overlap",
+			prefix: "",
+			value:  "abcde",
+			expectedResult: MaskedIdentifier{
+				Prefix:            "",
+				ValueLength:       5,
+				MaskedValuePrefix: "a",
+				MaskedValueSuffix: "bcde",
+			},
+		},
+		{
+			name:   "success: value medium (6), prefix val len fits exactly",
+			prefix: "pk_",
+			value:  "abcdef",
+			expectedResult: MaskedIdentifier{
+				Prefix:            "pk_",
+				ValueLength:       6,
+				MaskedValuePrefix: "ab",
+				MaskedValueSuffix: "cdef",
+			},
+		},
+	}
+
+	for _, tc := range testCases {
+		t.Run(tc.name, func(t *testing.T) {
+			t.Parallel()
+			result, err := MaskKey(tc.prefix, tc.value)
+
+			if tc.expectedErrString != "" {
+				require.EqualError(t, err, tc.expectedErrString)
+				assert.Equal(t, tc.expectedResult, result)
+			} else {
+				require.NoError(t, err)
+				assert.Equal(t, tc.expectedResult, result)
+			}
+		})
+	}
+}