feat(config): unify mpv plugin options under main config and add CSS/Ani

- Replace subminer.conf plugin config with mpv.* fields in config.jsonc
- Add socketPath, backend, autoStartSubMiner, pauseUntilOverlayReady, aniskipEnabled/buttonKey, subminerBinaryPath to mpv config
- Add subtitleSidebar.css field; migrate legacy sidebar appearance fields
- Add paintOrder and WebkitTextStroke to subtitle style options
- Update default subtitle/sidebar fontFamily to CJK-first stack
- Fix overlay visible state surviving mpv y-r restart
- Fix live config saves applying subtitle CSS immediately to open overlays
- Migrate legacy primary/secondary subtitle appearance into subtitleStyle.css on load
- Switch AniSkip button key setting to click-to-learn key capture

plugin/subminer/process.lua

@@ -199,7 +199,10 @@ function M.create(ctx)
 			table.insert(args, "--socket")
 			table.insert(args, socket_path)
 
-			local should_show_visible = resolve_visible_overlay_startup()
+			local should_show_visible = overrides.show_visible_overlay
+			if should_show_visible == nil then
+				should_show_visible = resolve_visible_overlay_startup()
+			end
 			if should_show_visible then
 				table.insert(args, "--show-visible-overlay")
 			else
@@ -506,7 +509,9 @@ function M.create(ctx)
 			state.texthooker_running = false
 			disarm_auto_play_ready_gate()
 
-			local start_args = build_command_args("start")
+			local start_args = build_command_args("start", {
+				show_visible_overlay = true,
+			})
 			subminer_log("info", "process", "Starting overlay: " .. table.concat(start_args, " "))
 
 			state.overlay_running = true