Introduce Individual Contributor License Agreement (ICLA) to enable
dual licensing (LGPL-V3 open source + future closed-source releases).
- CLA.md: Apache ICLA-style license grant with moral rights waiver,
patent license, electronic signature clause, and assignability
- .github/workflows/cla.yml: CLA Assistant Lite bot that auto-checks
PRs, posts signing prompts, and stores signatures on a separate
`cla-signatures` branch to keep main branch history clean
