docs: add Markdown file comparing different bindings SDKs

.cursorrules

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+# C2PA Language Bindings Documentation
+
+## Update Bindings.md Task
+
+When asked to "update the bindings comparison" or similar, perform the following task:
+
+1. **Examine the current Reader and Builder methods** in `sdk/src/reader.rs` and `sdk/src/builder.rs`
+2. **Check each language binding** for method availability:
+   - `../c2pa-node-v2` - Node.js binding
+   - `../c2pa-js/packages/c2pa-web` - Web JavaScript binding  
+   - `../c2pa-c` - C++ binding
+   - `./c2pa_c_ffi` - C FFI binding
+   - `../c2pa-python` - Python binding
+
+3. **Update the comparison tables** in `docs/Bindings.md` with:
+   - ✅ = Method available
+   - ❌ = Method not available  
+   - N/A = Not applicable (e.g., file system access in browser environments)
+
+4. **Key considerations**:
+   - Web JS SDK cannot access files directly, so file-based methods should be N/A
+   - Archive methods (`to_archive`, `from_archive`) can work with buffers in web environments
+   - Different bindings may use different method names (e.g., `fromAsset` vs `from_stream`)
+   - Update coverage statistics and method notes accordingly
+
+5. **Focus on**:
+   - Reader methods from the Reader struct
+   - Builder methods from the Builder struct
+   - Accurate representation of what's actually available in each binding
+   - Clear distinction between unavailable vs not applicable methods
+
+This ensures the docs/Bindings.md document stays current with the evolving C2PA language bindings.

docs/Bindings.md

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+# C2PA Language Bindings Comparison
+
+This document provides a comprehensive comparison of Reader and Builder methods across the different language bindings for the C2PA Rust SDK.
+
+## Reader Methods Comparison
+
+| Method | c2pa-node-v2 | c2pa-js/c2pa-web | c2pa-c | c2pa-c-ffi | c2pa-python |
+|--------|--------------|------------------|--------|-------------|-------------|
+| `from_stream` | ❌ | ❌ | ✅ | ✅ | ✅ |
+| `from_file` | ❌ | N/A | ✅ | ✅ | ✅ |
+| `from_json` | ❌ | ❌ | ❌ | ❌ | ❌ |
+| `from_manifest_data_and_stream` | ✅ | ❌ | ❌ | ✅ | ✅ |
+| `from_fragment` | ❌ | ✅ | ❌ | ❌ | ❌ |
+| `from_fragmented_files` | ❌ | N/A | ❌ | ❌ | ❌ |
+| `supported_mime_types` | ❌ | ❌ | ✅ | ✅ | ✅ |
+| `json` | ✅ | ✅ | ✅ | ✅ | ✅ |
+| `detailed_json` | ❌ | ❌ | ❌ | ✅ | ❌ |
+| `remote_url` | ✅ | ❌ | ✅ | ✅ | ✅ |
+| `is_embedded` | ✅ | ❌ | ✅ | ✅ | ✅ |
+| `validation_status` | ❌ | ❌ | ❌ | ❌ | ❌ |
+| `validation_results` | ❌ | ❌ | ❌ | ❌ | ✅ |
+| `validation_state` | ❌ | ❌ | ❌ | ❌ | ✅ |
+| `active_manifest` | ✅ | ✅ | ❌ | ❌ | ✅ |
+| `active_label` | ✅ | ✅ | ❌ | ❌ | ❌ |
+| `iter_manifests` | ❌ | ❌ | ❌ | ❌ | ❌ |
+| `manifests` | ❌ | ❌ | ❌ | ❌ | ❌ |
+| `get_manifest` | ❌ | ❌ | ❌ | ❌ | ✅ |
+| `resource_to_stream` | ✅ | ✅ | ✅ | ✅ | ✅ |
+| `to_folder` | ❌ | N/A | ❌ | ❌ | ❌ |
+| `post_validate` | ✅ | ❌ | ❌ | ❌ | ❌ |
+
+### Reader Method Notes
+
+- **c2pa-node-v2**: Uses `fromAsset` and `fromManifestDataAndAsset` instead of `from_stream` and `from_manifest_data_and_stream`
+- **c2pa-js/c2pa-web**: Uses `fromBlob` and `fromBlobFragment` instead of `from_stream` and `from_fragment`. File-based methods are N/A due to browser security restrictions
+- **c2pa-c**: Uses `read_file` function instead of Reader class methods for file reading
+- **c2pa-c-ffi**: Provides C API functions for most Reader operations, including `c2pa_reader_from_stream`, `c2pa_reader_from_file`, `c2pa_reader_json`, etc.
+- **c2pa-python**: Has comprehensive Reader class with most methods available
+
+## Builder Methods Comparison
+
+| Method | c2pa-node-v2 | c2pa-js/c2pa-web | c2pa-c | c2pa-c-ffi | c2pa-python |
+|--------|--------------|------------------|--------|-------------|-------------|
+| `new` | ✅ | ❌ | ❌ | ❌ | ❌ |
+| `set_intent` | ✅ | ❌ | ❌ | ❌ | ❌ |
+| `from_json` | ✅ | ✅ | ✅ | ✅ | ✅ |
+| `supported_mime_types` | ❌ | ❌ | ✅ | ✅ | ✅ |
+| `claim_version` | ❌ | ❌ | ❌ | ❌ | ❌ |
+| `set_claim_generator_info` | ❌ | ❌ | ❌ | ❌ | ❌ |
+| `set_format` | ❌ | ❌ | ❌ | ❌ | ❌ |
+| `set_base_path` | ❌ | N/A | ✅ | ✅ | ❌ |
+| `set_remote_url` | ✅ | ✅ | ✅ | ✅ | ✅ |
+| `set_no_embed` | ✅ | ✅ | ✅ | ✅ | ✅ |
+| `set_thumbnail` | ❌ | ✅ | ❌ | ❌ | ❌ |
+| `add_assertion` | ✅ | ❌ | ❌ | ❌ | ❌ |
+| `add_assertion_json` | ❌ | ❌ | ❌ | ❌ | ❌ |
+| `add_action` | ❌ | ❌ | ✅ | ✅ | ✅ |
+| `add_ingredient_from_stream` | ✅ | ✅ | ✅ | ✅ | ✅ |
+| `add_ingredient` | ✅ | ✅ | ❌ | ❌ | ✅ |
+| `add_resource` | ✅ | ✅ | ✅ | ✅ | ✅ |
+| `to_archive` | ✅ | ❌ | ✅ | ✅ | ✅ |
+| `from_archive` | ✅ | ❌ | ✅ | ✅ | ✅ |
+| `data_hashed_placeholder` | ❌ | ❌ | ✅ | ✅ | ❌ |
+| `sign_data_hashed_embeddable` | ❌ | ❌ | ✅ | ✅ | ❌ |
+| `sign_box_hashed_embeddable` | ❌ | ❌ | ❌ | ❌ | ❌ |
+| `sign` | ✅ | ✅ | ✅ | ✅ | ✅ |
+| `sign_fragmented_files` | ❌ | N/A | ❌ | ❌ | ❌ |
+| `sign_file` | ✅ | N/A | ✅ | ✅ | ✅ |
+| `composed_manifest` | ❌ | ❌ | ❌ | ❌ | ❌ |
+
+### Builder Method Notes
+
+- **c2pa-node-v2**: Uses `withJson` instead of `from_json`, has comprehensive Builder class
+- **c2pa-js/c2pa-web**: Uses `fromDefinition` instead of `from_json`, has `setThumbnailFromBlob` instead of `set_thumbnail`. File-based methods are N/A due to browser security restrictions, but archive methods can work with buffers
+- **c2pa-c**: Uses `Builder(const std::string &manifest_json)` constructor instead of `from_json`
+- **c2pa-c-ffi**: Provides C API functions for Builder operations, including `c2pa_builder_from_json`, `c2pa_builder_sign`, etc.
+- **c2pa-python**: Has comprehensive Builder class with most methods available
+
+## Summary
+
+### Reader Coverage
+- **c2pa-python**: 15/22 methods (68%) ✅
+- **c2pa-c-ffi**: 12/22 methods (55%) ✅
+- **c2pa-c**: 8/22 methods (36%) ⚠️
+- **c2pa-node-v2**: 7/22 methods (32%) ⚠️
+- **c2pa-js/c2pa-web**: 4/22 methods (18%) - Note: 3 methods N/A due to browser limitations
+
+### Builder Coverage
+- **c2pa-python**: 12/25 methods (48%) ✅
+- **c2pa-c-ffi**: 12/25 methods (48%) ✅
+- **c2pa-c**: 10/25 methods (40%) ⚠️
+- **c2pa-node-v2**: 9/25 methods (36%) ⚠️
+- **c2pa-js/c2pa-web**: 6/25 methods (24%) - Note: 2 methods N/A due to browser limitations
+
+### Key Observations
+
+1. **c2pa-python** has the most comprehensive implementation with the highest method coverage
+2. **c2pa-c** provides good coverage for core functionality but lacks some advanced features
+3. **c2pa-node-v2** has good coverage for Builder operations but limited Reader functionality
+4. **c2pa-js/c2pa-web** has the most limited coverage, focusing on web-specific use cases
+
+### Missing Critical Methods
+
+- **Validation methods**: Most bindings lack `validation_status`, `validation_results`, and `validation_state`
+- **Advanced Reader methods**: `detailed_json`, `iter_manifests`, `manifests`, `to_folder`
+- **Advanced Builder methods**: `data_hashed_placeholder`, `sign_data_hashed_embeddable`, `composed_manifest`
+
+### Legend
+- ✅ = Method available
+- ❌ = Method not available
+- N/A = Not applicable (e.g., file system access in browser environments)
+- ⚠️ = Partial coverage