refactor(RichTextViewer): move isMarkdown onto RichTextViewerState

Cleaner conceptual model: the parsed state object is the place where
all derived facts about the content live, so `isMarkdown` becomes a
field on `RichTextViewerState` (populated by `RichTextParser.parseText`
using the same cheap heuristic).

`RichTextViewer` now calls `CachedRichTextParser.parseText` once at the
top and dispatches on `state.isMarkdown` instead of running a separate
scan. `CachedRichTextParser.isMarkdown(content)` and its dedicated
`isMarkdownCache` go away — the single `richTextCache` carries the
decision alongside the parsed segments.

Inner callers (`DisplaySecretEmoji`, `MultiSetCompose` reaction
preview, `DisplayUncitedHashtags`) are unaffected: they continue to
receive a fully-parsed state with all segments populated.

amethyst/src/main/java/com/vitorpamplona/amethyst/service/CachedRichTextParser.kt

@@ -28,7 +28,6 @@ import com.vitorpamplona.amethyst.commons.richtext.UrlParser
 
 object CachedRichTextParser {
     private val richTextCache = LruCache<Int, RichTextViewerState>(50)
-    private val isMarkdownCache = LruCache<Int, Boolean>(200)
 
     private fun hashCodeCache(
         content: String,
@@ -70,25 +69,6 @@ object CachedRichTextParser {
             newUrls
         }
     }
-
-    // Shared across every RichTextViewer instance so that the same content quoted in multiple
-    // notes only pays for the scan once. The decision is purely a function of `content`.
-    fun isMarkdown(content: String): Boolean {
-        val key = content.hashCode()
-        isMarkdownCache[key]?.let { return it }
-        val result = computeIsMarkdown(content)
-        isMarkdownCache.put(key, result)
-        return result
-    }
-
-    private fun computeIsMarkdown(content: String): Boolean =
-        content.startsWith("> ") ||
-            content.startsWith("# ") ||
-            content.contains("##") ||
-            content.contains("__") ||
-            content.contains("**") ||
-            content.contains("```") ||
-            content.contains("](")
 }
 
 object CachedUrlParser {

amethyst/src/main/java/com/vitorpamplona/amethyst/ui/components/RichTextViewer.kt

@@ -136,7 +136,11 @@ fun RichTextViewer(
     nav: INav,
 ) {
     Column(modifier = modifier) {
-        if (remember(content) { CachedRichTextParser.isMarkdown(content) }) {
+        val state =
+            remember(content, tags) {
+                CachedRichTextParser.parseText(content, tags, callbackUri, authorPubKey)
+            }
+        if (state.isMarkdown) {
             RenderContentAsMarkdown(content, tags, canPreview, quotesLeft, backgroundColor, callbackUri, accountViewModel, nav)
         } else {
             RenderRegular(content, tags, canPreview, quotesLeft, backgroundColor, callbackUri, authorPubKey, accountViewModel, nav)

commons/src/commonMain/kotlin/com/vitorpamplona/amethyst/commons/richtext/RichTextParser.kt

@@ -224,6 +224,7 @@ class RichTextParser {
             customEmoji = emojiMap.toImmutableMap(),
             paragraphs = segments,
             tags = tags,
+            isMarkdown = isMarkdown(content),
         )
     }
 
@@ -411,6 +412,18 @@ class RichTextParser {
     }
 
     companion object {
+        // Cheap heuristic: stored on the parsed state so callers (e.g. RichTextViewer's
+        // markdown vs regular dispatch) can read the decision off the cached result instead
+        // of running a separate scan + maintaining a separate cache.
+        fun isMarkdown(content: String): Boolean =
+            content.startsWith("> ") ||
+                content.startsWith("# ") ||
+                content.contains("##") ||
+                content.contains("__") ||
+                content.contains("**") ||
+                content.contains("```") ||
+                content.contains("](")
+
         val longDatePattern: Regex = Regex("^\\d{4}-\\d{2}-\\d{2}$")
         val shortDatePattern: Regex = Regex("^\\d{2}-\\d{2}-\\d{2}$")
 

commons/src/commonMain/kotlin/com/vitorpamplona/amethyst/commons/richtext/RichTextParserSegments.kt

@@ -33,6 +33,7 @@ class RichTextViewerState(
     val customEmoji: ImmutableMap<String, String>,
     val paragraphs: ImmutableList<ParagraphState>,
     val tags: ImmutableListOfLists<String>,
+    val isMarkdown: Boolean = false,
 )
 
 @Immutable