Feature: text glow rendering and an "outline all text" option

[Shuro]

What

• Render game-specified glow colours as text outlines. Chat messages that carry a UIGlow payload (e.g. the red "Dalamud" in the welcome message, duty/collectable notices) now render with their outline in Chat 2, matching vanilla chat. Toggleable via a new Render glow option (on by default).
• New "Outline all text" option (off by default): draws a configurable outline around all chat text for readability, with a colour picker and a reset button in the Fonts settings tab.

How

The outline is drawn by stamping the text into the window draw list 8 times at ±1px offsets before the text itself is drawn (ImGuiUtil.DrawTextGlow).

Two details were needed to actually match vanilla rendering (verified by pixel-level comparison of vanilla vs Chat 2 screenshots):

1. Glow colours resolve via the dark-theme UIColor variant. The UIColor sheet columns (Dark, Light, ClassicFF, …) are per-UI-theme variants of one colour. Using .Light yields pastel light-theme colours (a red glow rendered as salmon-pink); .Dark matches what vanilla chat displays, consistent with how foreground colours are already resolved.
2. Glow alpha is scaled by 0x66/0xFF per stamp. Vanilla's glow peaks at ~85% opacity with a soft falloff. Game glow payloads are fully opaque, and overlapping stamps compound alpha (two stamps at 85% already composite to ~98%), producing a hard solid ring instead of a glow. Scaling each stamp to 0x66 makes the composite across overlapping stamps land at vanilla's ~85% peak — measured within ~1% of vanilla on identical test messages. The default outline colour for Outline all text is 0x00000066 for the same reason.

Disclosure:
This was co-developed with AI assistance (Claude Code).
I've reviewed the code and tested it in game myself.

Screenshots

Vanilla	Chat 2

[Shuro]

Thanks for the hint in Discord regarding the broken alpha handling on raw values.
Reworked it in the latest commit:

Glow alpha no longer derived from the pushed color (ImGuiUtil.cs)
The game ignores the alpha byte of pushed edge colors entirely and always renders them fully opaque, for both EdgeColorType sheet lookups and raw EdgeColor values. So the glow now takes only the RGB from the pushed color and uses a fixed per-stamp alpha (0x66), whose composite over the 8 outline stamps matches the vanilla glow strength.

Raw EdgeColor macros are now actually parsed (ExtraPayload.cs, ChunkUtil.cs)
Previously any raw 0x14 payload just popped the glow stack. ColorPayload now handles both Color and EdgeColor and decodes all expression forms: packed ints (3- and 4-byte), gnum global parameters, inline small integers, and stackcolor pops. Values resolving to 0 are pushed as real "no glow" entries, that's what the game does (verified below), and it keeps the stack balanced for the matching stackcolor pop.

Pushed colors are forced opaque (ColourUtil.cs)
ArgbToRgba previously only forced alpha when the byte was absent, so something like color(0x05FF0000) rendered near-invisible text. Alpha is now forced to 0xFF for any nonzero pushed value, matching the game.

Hardening (ChunkUtil.cs)
UIForeground/UIGlow payloads referencing rows missing from the UIColor sheet used to throw and drop the whole message; they're now handled gracefully.

Debugger (SeStringDebugger.cs)
The SeString debugger now decodes EdgeColor payloads as well and labels which macro family a color payload came from.

Everything was validated side-by-side against the vanilla renderer by printing hand-crafted payloads (packed RGBA with and without alpha, gnum, literals, stackcolor chains, invalid sheet rows) to the native log and comparing, the two now render identically.