Upstream proxy-wasm-cpp-sdk module@0.0.0-250925-e5256b0.envoy to BCR (new module)

### Module
- `proxy-wasm-cpp-sdk`
- Version: 0.0.0-250925-e5256b0.envoy
- BCR: ❌ Not present
- Source: https://github.com/proxy-wasm/proxy-wasm-cpp-sdk (has MODULE.bazel upstream)

### Patches Applied
- `proxy-wasm-cpp-sdk.patch` — disables memory growth/initial heap flags in wasm builds

### Checklist
- [x] Review upstream MODULE.bazel vs toolshed version
- [x] PR to upstream with patch fixes if applicable
- [x] PR to BCR for new module onboarding
- [x] Coordinate with proxy-wasm maintainers
- [ ] Update envoy build to use BCR module when live

### Notes
- Blockers: Getting upstream agreement on MODULE.bazel and patches
- Patch: https://github.com/envoyproxy/toolshed/blob/main/bazel-registry/modules/proxy-wasm-cpp-sdk/0.0.0-250925-e5256b0.envoy/patches/proxy-wasm-cpp-sdk. patch