exclude tip from TipOptions (#2459)

[cpruijsen]

Fixes #2459.

MarkOptions.tip is typed as TipOptions, and TipOptions extended MarkOptions, so nested tip objects typechecked:

Plot.dot(penguins, {x: "culmen_length_mm", y: "culmen_depth_mm", tip: {tip: {tip: {}}}})

The tip mark cannot have a nested tip. The constructor already forces tip: false when options.tip is truthy. This change makes TipOptions extend Omit<MarkOptions, "tip"> so the types match that.

Decision

• Chose: drop tip from TipOptions itself.
• Alternative: keep TipOptions extends MarkOptions and omit tip only on the object type of MarkOptions.tip.
• Reasoning: this is what [Types] Wrong recursion in Mark’s _tip_ option #2459 asked for, and it matches how Plot.tip() behaves at runtime. RasterOptions already uses Omit<MarkOptions, …> for options a mark cannot use.
• Happy to switch to the narrower Omit on MarkOptions.tip if you would rather leave Plot.tip(data, { tip: false }) typechecking as a no-op.

No runtime or docs change; the tip-mark docs never listed a tip option on Plot.tip().

Test plan

• Plot.dot([], { tip: { tip: true } }) is a type error
• Plot.tip([], { tip: true }) is a type error
• Plot.dot([], { tip: true }) still typechecks
• Plot.dot([], { tip: { anchor: "top", pointer: "xy" } }) still typechecks
• Plot.tip([], { x: 0, y: 0, anchor: "top" }) still typechecks