ci: add file hygiene workflow and lint configuration
Add reusable file-hygiene workflow caller and canonical lint configs:
- .github/workflows/file-hygiene.yml: caller for lint-files.yml
- .editorconfig: UTF-8 (no BOM), LF line endings, indent rules
with indent_size=4 override for Kotlin (*.kt, *.kts)
- .gitattributes: LF normalization for text files, binary rules
- .markdownlint.yml + .markdownlint-cli2.yaml: markdown lint rules
with secp256k1-kmp/native/secp256k1/ excluded
- .yamllint.yml: YAML lint rules with relaxations
Refs: hyperledger-identus/hyperledger-identus#172
Co-Authored-By: Claude Opus 4.6 (1M context) <[email protected]>
Signed-off-by: Yurii Shynbuiev <[email protected]>