Restructure modules with per-module addon subdirs

- Each module (outline, interact, screenshot) now has its own addon/
  subdir with .toc, .lua, and Bindings.xml
- Core WeirdUtils addon lives in src/core/addon/
- build.zig supports compile-time feature gating via -D options
- main.zig uses build_options for conditional imports and addon embedding
- Module addons only load when their module is compiled in
- 'zig build all-variants' produces full.dll + 3 single-module DLLs

src/outline/addon/Outline.lua

@@ -0,0 +1,37 @@
+-- Outline addon (embedded in DLL, loaded from memory)
+-- Part of WeirdUtils - only loaded when outline module is compiled
+
+OUTLINE_VERSION = 1
+
+BINDING_HEADER_OUTLINE = "Outline"
+
+local frame = CreateFrame("Frame")
+frame:RegisterEvent("ADDON_LOADED")
+frame:RegisterEvent("PLAYER_LOGIN")
+
+frame:SetScript("OnEvent", function()
+    if event == "PLAYER_LOGIN" then
+        local on = OutlineCommand()
+        DEFAULT_CHAT_FRAME:AddMessage("|cff00ff00Outline|r v" .. OUTLINE_VERSION .. " loaded (" .. (on and "enabled" or "disabled") .. ")")
+    end
+end)
+
+SLASH_OUTLINE1 = "/outline"
+SLASH_OUTLINE2 = "/ol"
+SlashCmdList["OUTLINE"] = function(msg)
+    msg = string.lower(msg or "")
+    if msg == "" or msg == "status" then
+        local on = OutlineCommand()
+        DEFAULT_CHAT_FRAME:AddMessage("Outlines: " .. (on and "|cff00ff00ON|r" or "|cffff0000OFF|r"))
+    elseif msg == "on" or msg == "enable" then
+        OutlineCommand("on")
+        DEFAULT_CHAT_FRAME:AddMessage("Outlines |cff00ff00enabled|r")
+    elseif msg == "off" or msg == "disable" then
+        OutlineCommand("off")
+        DEFAULT_CHAT_FRAME:AddMessage("Outlines |cffff0000disabled|r")
+    else
+        DEFAULT_CHAT_FRAME:AddMessage("|cff00ff00Outline|r commands:")
+        DEFAULT_CHAT_FRAME:AddMessage("  /ol - Show status")
+        DEFAULT_CHAT_FRAME:AddMessage("  /ol on|off - Toggle outlines")
+    end
+end