Initial release: Go Jdenticon library v0.1.0

- Core library with SVG and PNG generation
- CLI tool with generate and batch commands
- Cross-platform path handling for Windows compatibility
- Comprehensive test suite with integration tests

internal/constants/limits.go

@@ -0,0 +1,22 @@
+package constants
+
+// Default security limits for DoS protection.
+// These constants define safe default values for user inputs to prevent
+// denial of service attacks through resource exhaustion while remaining configurable.
+
+// DefaultMaxIconSize is the default maximum dimension (width or height) for a generated icon.
+// A 4096x4096 RGBA image requires ~64MB of memory, which is generous for legitimate
+// use while preventing unbounded memory allocation attacks.
+// This limit is stricter than the JavaScript reference implementation for enhanced security.
+const DefaultMaxIconSize = 4096
+
+// DefaultMaxInputLength is the default maximum number of bytes for the input string to be hashed.
+// 1MB is sufficient for any reasonable identifier and prevents hash computation DoS attacks.
+// Input strings longer than this are rejected before hashing begins.
+const DefaultMaxInputLength = 1 * 1024 * 1024 // 1 MB
+
+// DefaultMaxComplexity is the default maximum geometric complexity score for an identicon.
+// This score is calculated as the sum of complexity points for all shapes in an identicon.
+// A complexity score of 100 allows for diverse identicons while preventing resource exhaustion.
+// This value may be adjusted based on empirical analysis of typical identicon complexity.
+const DefaultMaxComplexity = 100