Libraries concept doc and override docs

[sarina]

New documentation:

• Override the Title of Library-Sourced Content
• Override Text Content in a Library-Referenced Component
• Override Text Content in a Library-Sourced Structural Block
• Concept Doc on Content Libraries

AI Disclaimer

I used Claude liberally in writing these docs, with only light edits as I'm not very familiar with the overrides feature. However I thought the Concept doc was pretty great as generated. Claude chat log

Notes to Reviewers

Please provide any necessary screenshots and I will incorporate them.

Please respond to document questions about Claude's assumptions.

[sarina]

Gaps to verify before publishing:

• The actual UI button labels — I used :guilabel:Edit and :guilabel:Save based on the spec description, but you'll want to confirm the exact labels in the Ulmo UI.
• Whether the prerequisite about "published" library content is correct — the issue spec says the component needs to be published in the library first.

[sarina]

Decisions made: I split the steps by content type because the UI entry point is different — the course outline for structural content vs. the unit view for components. The spec doesn't describe the exact UI mechanics (pencil icon, click-to-edit, etc.), so those are reasonable assumptions based on how Studio typically works and should be verified against the actual Verawood UI.

Gaps to verify:

• The exact UI interaction for renaming (pencil icon vs. double-click vs. a settings panel) — the spec doesn't specify, only that titles should be "editable."
• Whether the rename UI differs between the course outline and unit views in any meaningful way that would require additional steps.

[sarina]

Gaps to verify before publishing:

• The UI entry point — whether the text component is accessible for editing directly from within a library-sourced unit in the unit view, or if there are any extra navigation steps required.
• Whether "structural block" is the term used in the Studio UI, or whether the product uses "section," "subsection," and "unit" exclusively. If users won't recognize "structural block," the title and intro may need adjusting.