feat(skills): add publish subcommand for skills registry [CRF-1144]

[amirulabu]

Summary

Adds wukong skills publish — an interactive wizard for uploading a local skill from .agents/skills/<name>/SKILL.md to the internal skills registry via the new publishSkill GraphQL mutation on wukong-api-proxy.

Jira: CRF-1144 — [CLI] wukong skills push — Publish a local skill to the registry

Behavior

Interactive wizard that guides the user through publishing a skill:

• Discovers local skills under .agents/skills/<name>/SKILL.md
• Prompts for skill slug and commit message
• Validates SKILL.md frontmatter before publishing
• Pushes to the GitHub registry under <skill-slug>/SKILL.md
• Maps known server errors to friendly messages
• Confirms success and outputs the published location

Changes

• SDK: hand-patch schema.json with publishSkill + SkillPublishResult; add PublishSkill mutation and publish_skill SDK method.
• CLI: WKClient wrapper with api_event telemetry; new interactive publish.rs handler.
• Docs + completion snapshots updated.

Test plan

• cargo build succeeds
• cargo test passes (snapshot updates verified)
• wukong skills publish end-to-end against staging registry
• Verify error messages for: missing SKILL.md, invalid frontmatter, slug already exists, auth failure