[web-shared] Traceviewer Sidepanel improvements/bugfixes

[karthikscale3]

Summary of changes

Tested everything on local and vercel o11y - 90% UI changes, 10% bugfixes

• Restyled the trace side panel to match logs-page UI more closely (header/action/details spacing, row typography, separators, close button treatment).
• Added header navigation controls (Up/Down) to move between selected spans, with disabled boundary states.
• Reworked attribute rows for logs-like layout (better font sizing, spacing, inset dividers, truncation behavior for long values).
• Added moduleSpecifier UX: truncate in row, click to copy full value with toast.
• Added shared copyable JSON inspector block (new common component) used by both attribute JSON and event JSON payloads.
• Added loading skeletons for Input / Output / Event Data and event-loading states.
• Fixed input wording/pluralization (Input (1 argument) vs arguments) and standardized label capitalization.
• Enhanced input rendering to include closureVars and thisVal when defined.

Before

After