ux polish batch: truncate titles, th sort a11y, mobile drawer, nav icons, dead code

[ajianaz]

Summary

A batch of small, verified usability/a11y fixes that are each tiny but add up to most of the remaining friction.

Items (all verified 2026-09-20)

1. Truncate without title — content clipped with no way to read it in place:
   • dashboard/+page.svelte:319 (post caption), :345 (schedule caption), media/+page.svelte:363 (filename)
2. Sortable <th> not keyboard accessible — lib/components/DataTable.svelte:124-132: <th onclick> without tabindex/onkeydown/aria-sort. (Rows are done right: role=button + tabindex + Enter/Space + inner-control guard.)
3. Mobile sidebar drawer: no Escape-to-close, no body scroll lock — admin/+layout.svelte (hamburger/backdrop exist; MediaLightbox already implements both correctly — copy that pattern).
4. Nav icon duplication — Comments and Mentions both use MessageSquare (+layout.svelte:91-92) → switch Mentions to AtSign.
5. Emoji in chrome — 🕒 in sidebar footer (+layout.svelte:167) is the only emoji in an otherwise Lucide-icon UI → <Clock>.
6. Raw backend error strings in toasts — pattern toast(e.message || 'Fallback', 'error') surfaces raw API errors; normalize to human copy (+ error code) with the detail kept for console.
7. Dead code — account switcher state/handler/CSS never rendered (+layout.svelte:28-43, 194-214, localStorage 'titen.activeAccount' unused elsewhere); StatSkeleton unused label prop + invalid h-2.4 class (h-2.4 is not a Tailwind step → dropped, no height).

Fix

See items; each is ≤ 10 lines.

Acceptance criteria

• All clipped text has title={...}.
• Column sorting works via keyboard; aria-sort reflects state.
• Escape closes mobile drawer; body scroll locked while open.
• Mentions nav uses AtSign; no emoji in chrome.
• Switcher dead code removed; StatSkeleton fixed.
• Build + svelte-check clean.

Source: Titen UX audit 2026-09-20 (findings M4, M5, M6, L1-L4).

[ajianaz]

Implemented in PR #278 (merged 2026-09-20, commit 57c101f) — UX audit remediation batch.