feat(web): Shiki at build time replaces the regex highlighter; postfix #if sits flush

Shiki 4 runs in a Vite plugin over the snippets in copy.ts and hands the
page finished markup through a virtual module: no grammar or engine ships.
The theme is the page's own, written against the scopes the Swift, Markdown
and shell grammars emit, with colours replaced by the palette's CSS
variables so both themes are one theme. One transformer does what the Swift
grammar cannot: colour a capitalised name in call or member position as a
type, as Xcode does. Tests pin the roles against the real grammars.

The iOS snippet, README and doc comment now indent the modifier inside
#if/#endif rather than the directives themselves, per SE-0308 and Xcode.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

Author: angusbezzina

README.md

@@ -81,9 +81,9 @@ struct MyApp: App {
 
 ```swift
 ContentView()
-    #if DEBUG
+#if DEBUG
     .installAnnotation()
-    #endif
+#endif
 ```
 
 UIKit iOS hosts call `Annotation.install()` from the scene delegate once the

Sources/AnnotKit/iOS/InstallAnnotation.swift

@@ -5,9 +5,9 @@ import SwiftUI
 /// tree. Dev-gated like ``Annotation/install(source:sink:)``.
 ///
 ///     ContentView()
-///         #if DEBUG
+///     #if DEBUG
 ///         .installAnnotation()
-///         #endif
+///     #endif
 public extension View {
     func installAnnotation(sink: AnnotationSink? = nil) -> some View {
         onAppear { Annotation.install(sink: sink) }