Docs sidebar lacks visual hierarchy and stays fully expanded (flat list, verbose root label)

[nficano]

Summary

The sidebar reads as a flat list: group headers ("Guides", "Modules", "C# SDK API Reference") render at nearly the same weight/color as leaf links, so it's hard to scan. It also carries redundant chrome — a verbose "ARCP C# SDK documentation" root label and a duplicated "C# SDK API Reference" entry (the duplicate is tracked in #9) — and the long API symbol list is fully expanded rather than collapsible.

Location(s)

• Docs sidebar — app/layouts/docs.vue, all docs routes (worst on csharp/kotlin/typescript API trees).

Severity

P2 — IA / scannability.

Evidence

• Group headers and leaf links both compute to muted #756e62 — no weight/color distinction.
• "C# SDK API Reference" appears twice consecutively (section header + its own first child).
• API reference symbol list renders flat/expanded (hundreds of entries for kotlin/typescript).
• Screenshot: .audit/evidence/audit-docs-1280-csharp-getting-started.png.

Suggested fix

• Style group labels distinctly: ink #1b1815, mono, uppercase, ~11px, letter-spaced; leaf links at the darkened #5a5448.
• Shorten the doc-root label (e.g. "Overview").
• Collapse the API reference tree behind a disclosure (expand on the active trail).
• Dedupe the repeated node per Duplicate entries in sidebar navigation tree #9.

Acceptance criteria

• Clear visual distinction between group labels and leaf links
• API reference tree is collapsible, not a flat wall
• No duplicate/verbose root entries