chore: remove AGNTCY references, migrate to trusted publishing

[arpad-csepi]

Renames AGNTCY-branded references (copyright headers, README links, repository URLs, and the CLI's own extension key) to Agent-Card, and updates the release pipeline to trusted publishing.

• Copyright headers and repository field updated from github.com/agntcy/ai-catalog-cli to github.com/Agent-Card/ai-catalog-cli
• CLI_EXTENSION_KEY renamed from org.agntcy.ai-catalog-cli to org.agent-card.ai-catalog-cli (src/resolver.rs), bookkeeping extension key written to catalog entries
• README, CHANGELOG, SKILL.md, and demo scripts updated to reference the new org and release URLs
• release-rust.yaml: switched crates.io publishing to OIDC trusted publishing, removed the GH token secret, added id-token: write
• Bumped actions/checkout and other pinned action versions across CI workflows