docs(cycles): sweep marketplace job .md files and hook for 'Cycle' terminology

[CoreyRDean]

Follow-up from PR #107 author's known-limitations.

Problem

PR #107 introduced the "Cycle" marketing term in README + `marketplace/index.json` one-liners. Not yet updated:

1. Individual marketplace job files (`marketplace/*.md`) — their prose descriptions still use "job" in places.
2. The SessionStart hook (`~/.claude/hooks/scheduled-jobs-notice.sh`) — optional per docs: marketing brand — clauck's job primitive is a "Cycle" ("Clauck Cycles") #90 but would complete the user-facing surface.

Acceptance

• Sweep of `marketplace/*.md` files to use "Cycle" in human-facing prose (headers, descriptions). Leave technical terms (`job`, frontmatter field names, CLI commands) unchanged — per docs: introduce "Cycle" / "Clauck Cycles" brand term for scheduled jobs #107, brand term applies to marketing copy only.
• Update hook preamble to mention "Cycles" in user-facing lines; structured listing keeps "jobs" since it's agent-facing.
• No changes to CLI verbs, frontmatter, or code identifiers.