feat: bootstrap landscape group with landscape-jira skill

[jansdhillon]

Summary

Bootstraps the landscape group and contributes the first Landscape-specific skill: landscape-jira.

Changes

• groups/landscape/skills/landscape-jira/SKILL.md — skill for creating well-formed Jira issues in the LNDENG project. Covers all issue types (Story, Epic, Objective, Theme, Task, Spike, Bug, Sub-task, Project-Risk, Project-Issue) with IDs and hierarchy, plus:
  • Key field IDs including customfield_10614 (acceptance criteria, ADF format — common failure point)
  • How to look up the active sprint ID at call time rather than hardcoding it
  • Sprint as a plain integer (not an object)
  • ADF bullet list template for AC
  • The \n literal gotcha in ADF text nodes
  • Canonical guidance on writing good AC (user-centered, operational, system-centric)
  • Useful JQL patterns
• groups/landscape/collections.yaml — landscape-core collection including core + the skill
• CODEOWNERS — adds @canonical/landscape as owners of /groups/landscape/