Adjust dashboard slot scroll sizing (remove inner max-height clamp)

[multiplex55]

Motivation

• Allow the inner slot UI to grow to its natural content height while keeping the slot viewport fixed to body_height so nested content is not truncated or overlapped.
• Ensure clipping is applied to the visible viewport only, not to content-size calculations, to avoid interfering with layout.
• Keep the scroll area responsible for enforcing the viewport's maximum height so the overall slot layout remains stable.

Description

• In src/dashboard/dashboard.rs inside render_scrollable_widget the inner ui.set_max_height(body_height) was removed so the inner UI can compute its natural height.
• The slot clipping rect is now intersected with the scroll viewport (slot_clip.intersect(viewport)) and applied inside show_viewport so clipping affects only the viewport.
• The scroll area still uses ScrollArea::max_height(body_height) to keep the viewport height fixed, and ui.set_min_height(body_height) is retained on the inner UI to preserve minimum sizing.
• No other widget source files were modified; the change was limited to render_scrollable_widget / show_viewport behavior.

Testing

• No automated tests were executed for this change.
• Manual review inspected widgets with their own ScrollArea (e.g. todo, clipboard_recent, clipboard_snippets, recent_notes, notes_recent, process_list, query_list, tempfiles) and no code edits were required to avoid truncation after this change.

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Codex Task