Naming: rename the board sidebar — candidate "sideboard"

[ivanmkc]

What

The left panel that lists/switches between boards (currently headed "boards", #sidebar / <nav id=\"scopes\">) could use a more distinctive name. This issue tracks naming candidates.

Now that the panel does more than list — it sorts by Name / Created / Updated and shows per-board recency (#176) — it's becoming a real named surface, so a good name is worth settling.

Lead candidate: sideboard

A portmanteau of sidebar + board.

• 👍 Memorable, on-brand, playful; literally "the side panel of boards".
• 👍 Short, reads well as a UI label and in docs/code.
• 👎 Collides with the furniture sense ("a sideboard in the dining room") — minor, and unambiguous in context.

Other candidates to weigh

• board rail / rail — common UI term for a side strip
• board switcher — describes the action (switching boards)
• deck — "a deck of boards"
• boards panel — literal, safe, a bit plain
• boardbar — sidebar↔boardbar
• shelf — boards sitting on a shelf
• stack — a stack of boards

Decision checklist

• Pick the name (or keep "boards")
• Decide scope: just the visible heading/label, or also internal identifiers (#scopes, scope-* classes, "scope" in code/docs)?
• Update viewer UI label + any user-facing docs/README
• Note: "scope" → "board" was already done user-facing (feat(viewer): Share button — copy a deep link to the current scope #152); this would be the panel's own name

cc @ivanmkc — leaning sideboard; what's your call?

[ivanmkc]

Naming collision check for "sideboard"

• npm: the name sideboard is registered but dead — v0.6.0, last published 2018, ~8 downloads/week. (Description: "a library… to set your searchable data tables right" — adjacent domain, but abandoned.) ⇒ unusable as a future npm package name, irrelevant for an in-app panel label.
• GitHub: ~70 repos contain "sideboard" but none dominant — top hits are hardware (hoverboard-sideboard-hack), MAGFest's magfest/sideboard (6★ web framework), and Magic: The Gathering deck guides.
• Other senses: Magic: The Gathering term (the 15-card reserve) + furniture (dining cabinet).

Verdict: no major active project owns it; fine + distinctive as a UI/feature name. Only caveat: it's squatted (dead) on npm, so don't plan a package by that name.