Colour markdown's tables and the addresses written in it

A table is recognised by its delimiter row, the only line of one that cannot
be anything else, and its header is the line above -- the single place the
scanner looks ahead. Colouring every `|` instead would have marked the pipes
of a shell command written in a paragraph.

Addresses come in two shapes: `<...>` needs a scheme's colon or an at sign
inside it and no whitespace, which leaves `<div>` alone; a bare `scheme://`
needs no closer, so where it ends is the decision -- the sentence's trailing
punctuation is given back, and so is a closing bracket unless one opened
inside the URL.

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

app/androidApp/src/test/kotlin/com/example/aiapp/HighlighterTest.kt

@@ -255,6 +255,78 @@ class HighlighterTest {
         assertSpans(code, Language.MARKDOWN, Kind.METADATA, "(PLAN.md)")
     }
 
+    @Test
+    fun `a table is found by its delimiter row, and pipes elsewhere are plain`() {
+        val code = "| a | b |\n|---|---|\n| 1 | 2 |\n\nrun a | b in a paragraph"
+        assertSpans(
+            code,
+            Language.MARKDOWN,
+            Kind.MARK,
+            "|",
+            "|",
+            "|",
+            "|---|---|",
+            "|",
+            "|",
+            "|",
+        )
+    }
+
+    @Test
+    fun `a table without outer pipes still colours, and the table ends with the rows`() {
+        val code = "a | b\n--- | ---\nnot a row"
+        assertSpans(code, Language.MARKDOWN, Kind.MARK, "|", "--- | ---")
+    }
+
+    /**
+     * The tag in the last case is not an autolink and is left plain, but the address inside it is
+     * still an address and the bare-URL pass finds it. That is the intended reading: raw HTML is
+     * not something this scanner knows, and a URL is a URL wherever it was written.
+     */
+    @Test
+    fun `an autolink colours and an HTML tag does not`() {
+        val code = "<https://example.com> and <a@b.com> and <div> and <img src=\"http://x\">"
+        assertSpans(
+            code,
+            Language.MARKDOWN,
+            Kind.METADATA,
+            "<https://example.com>",
+            "<a@b.com>",
+            "http://x",
+        )
+    }
+
+    @Test
+    fun `a bare URL gives back the sentence's punctuation`() {
+        assertSpans(
+            "see https://example.com/a., and ssh://host/x)",
+            Language.MARKDOWN,
+            Kind.METADATA,
+            "https://example.com/a",
+            "ssh://host/x",
+        )
+    }
+
+    @Test
+    fun `a bracket a URL opened itself stays in it`() {
+        assertSpans(
+            "https://en.wikipedia.org/wiki/A_(b) here",
+            Language.MARKDOWN,
+            Kind.METADATA,
+            "https://en.wikipedia.org/wiki/A_(b)",
+        )
+    }
+
+    @Test
+    fun `a URL inside a link destination is not coloured twice`() {
+        assertSpans(
+            "[x](https://example.com)",
+            Language.MARKDOWN,
+            Kind.METADATA,
+            "(https://example.com)",
+        )
+    }
+
     @Test
     fun `a bracket with no destination after it is left plain`() {
         assertSpans("an [aside] here", Language.MARKDOWN, Kind.MARK)
@@ -305,6 +377,12 @@ class HighlighterTest {
                 "1.",
                 "[x](",
                 "#######",
+                "|",
+                "|---|",
+                "<",
+                "<>",
+                "http://",
+                "a://",
                 "\n\n   \n",
             )
         for (language in Language.entries) {