feat(translator): sanitize tool/function names for upstream provider compatibility

Implemented SanitizeFunctionName utility to ensure Claude tool names meet
Gemini/Upstream strict naming conventions (alphanumeric, starts with letter/underscore, max 64 chars).
Applied sanitization to tool definitions and usage in all relevant translators.

Co-authored-by: factory-droid[bot] <138933559+factory-droid[bot]@users.noreply.github.com>

internal/util/sanitize_test.go

@@ -0,0 +1,54 @@
+package util
+
+import (
+	"testing"
+)
+
+func TestSanitizeFunctionName(t *testing.T) {
+	tests := []struct {
+		name     string
+		input    string
+		expected string
+	}{
+		{"Normal", "valid_name", "valid_name"},
+		{"With Dots", "name.with.dots", "name.with.dots"},
+		{"With Colons", "name:with:colons", "name:with:colons"},
+		{"With Dashes", "name-with-dashes", "name-with-dashes"},
+		{"Mixed Allowed", "name.with_dots:colons-dashes", "name.with_dots:colons-dashes"},
+		{"Invalid Characters", "name!with@invalid#chars", "name_with_invalid_chars"},
+		{"Spaces", "name with spaces", "name_with_spaces"},
+		{"Non-ASCII", "name_with_你好_chars", "name_with____chars"},
+		{"Starts with digit", "123name", "_123name"},
+		{"Starts with dot", ".name", "_.name"},
+		{"Starts with colon", ":name", "_:name"},
+		{"Starts with dash", "-name", "_-name"},
+		{"Starts with invalid char", "!name", "_name"},
+		{"Exactly 64 chars", "this_is_a_very_long_name_that_exactly_reaches_sixty_four_charact", "this_is_a_very_long_name_that_exactly_reaches_sixty_four_charact"},
+		{"Too long (65 chars)", "this_is_a_very_long_name_that_exactly_reaches_sixty_four_charactX", "this_is_a_very_long_name_that_exactly_reaches_sixty_four_charact"},
+		{"Very long", "this_is_a_very_long_name_that_exceeds_the_sixty_four_character_limit_for_function_names", "this_is_a_very_long_name_that_exceeds_the_sixty_four_character_l"},
+		{"Empty", "", ""},
+		{"Single character invalid", "@", "_"},
+		{"Single character valid", "a", "a"},
+		{"Single character digit", "1", "_1"},
+		{"Single character underscore", "_", "_"},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			got := SanitizeFunctionName(tt.input)
+			if got != tt.expected {
+				t.Errorf("SanitizeFunctionName(%q) = %v, want %v", tt.input, got, tt.expected)
+			}
+			// Verify Gemini compliance
+			if len(got) > 64 {
+				t.Errorf("SanitizeFunctionName(%q) result too long: %d", tt.input, len(got))
+			}
+			if len(got) > 0 {
+				first := got[0]
+				if !((first >= 'a' && first <= 'z') || (first >= 'A' && first <= 'Z') || first == '_') {
+					t.Errorf("SanitizeFunctionName(%q) result starts with invalid char: %c", tt.input, first)
+				}
+			}
+		})
+	}
+}