Show CityStateType civilopedia text on CS Nation pages

[Fanfblrik]

Summary

Follow-up to #15271 / review note from @SomeTroglodyte: CityStateType is a RulesetObject with civilopediaText / uniques, but has no Civilopedia category.

• Surface type civilopediaText and type-level uniques on the city-state Nation civilopedia page (NationDescriptions.getCityStateInfo).
• Start bias […] from the type is not duplicated in the type-unique list — it already appears via Nation.getStartBias, using the same block as major civs (Terrain/… link, chain + terrain icons, civilopedia navigation).
• CS page layout aligned with major-civ Nation pages: no separator before start bias; friend/ally bonuses stay sub-indented; shared Color.toHexColor() helper (review).

(Screenshot file is for review only; can drop _pr_screenshots/ before merge.)

Test plan

• CityStateTypeCivilopediaOnNationTests
• Civilopedia → Nations → Bangkok (G&K Maritime CS): type line, When Friends/Allies bonuses, Start bias: Coast with Terrain/Coast link (click opens Coast terrain page)
• Mod CityStateType with civilopediaText / non-StartBias unique — both show on a CS of that type
• CI green

[SomeTroglodyte]

UI PR's need screenshots

[SomeTroglodyte]

Not yours, but
https://kotlinlang.org/docs/coding-conventions.html#horizontal-whitespace

Also, how often is such a conversion done in the current codebase 🤔 ? The luxury version exists here:

Unciv/core/src/com/unciv/ui/components/widgets/ColorMarkupLabel.kt

Lines 108 to 113 in bcd2a97

	private fun Color.toMarkup(): String {
	val mapEntry = inverseColorMap[this]
	if (mapEntry != null) return mapEntry
	if (a < 1f) return "#" + toString()
	return "#" + toString().substring(0,6)
	}

And another here:

Unciv/core/src/com/unciv/models/ruleset/tech/Era.kt

Line 117 in 03ca966

@Readonly fun getHexColor() = "#" + getColor().toString().substring(0, 6)

Might be worth a common extension.

[Fanfblrik]

Good catch on the spacing — fixed.

Also extracted a shared Color.toHexColor() next to colorFromRGB in Scene2dExtensions, and wired Era.getHexColor / ColorMarkupLabel.toMarkup / this call site through it.

[SomeTroglodyte]

Pity the @Cache/@LocalState way is blocked here, right?

See also: #15015, where it's done properly.

[Fanfblrik]

Yes — restoring @Readonly fails here because uniquesToCivilopediaTextLines (mutable overload) is not @Readonly. Left a short note pointing at #15015; once the FormattedLineListBuilder lands this is the obvious cleanup.

[SomeTroglodyte]

If it lands - I was hoping for some -any- feedback before I un-draft it, because converting existing code would be a lengthy chore. But then that was the trigger - seeing how many structurally different generators we cobbled together over time.

[yairm210]

In fact as of the latest version this is Readinly-able! This is exactly the scenario for @Mutated, passing mutation rights on to subfunctions!
https://yairm210.github.io/Purity/usage/advanced-usage/#mutating-input-parameters

[Fanfblrik]

Tried marking getCityStateInfo / uniquesToCivilopediaTextLines @Readonly with @Mutated lists. Purity still rejects it: the sequence overload calls non-Readonly SuspendFunction1.invoke, and the mutable overload calls non-Readonly Sequence.toCollection. Left as-is pending FormattedLineListBuilder (#15015) or Readonly-friendly helpers.