Add al-report-author leaf (wire into al-code-author)

[JesperSchulz]

Goal

Add the al-report-author leaf so al-code-author can generate a report (dataset + layout + request page) as part of a whole-PR code-artifact.

Build

• New action skill microsoft/skills/author/al-report-author.md, modelled on the existing author leaves and the DO composition contract (skills/do.md).
• Frontmatter: inputs: [object-spec], outputs: [code-artifact], no sub-skills (leaf).
• Register it in al-code-author's sub-skills list (R26 set-equality on the author folder).
• Encode the conventions: report object with dataset (dataitems/columns), a layout reference (RDLC or Word) via the modern rendering/DefaultRenderingLayout syntax, a request page with ApplicationArea on controls, ProcessingOnly where relevant, and UsageCategory/access for runnable reports.
• Self-select: return outcome: "not-applicable" for object-specs that aren't a report.

Acceptance

• Leaf authored + registered in al-code-author sub-skills.
• Validators green (0/0 incl. R26; index PASSED).
• Worked example in the skill's ## Output.

Refs

Part of author-leaf coverage (tracker + Epic). Object-type list: #34. Template + contract: #67.