fix(desktop): stop bare-URL autolinker swallowing trailing emphasis asterisks (#41093)

The desktop markdown preprocessor autolinks bare URLs by wrapping them in
<...>. RAW_URL_RE allowed '*' in its character classes, so a bold line with
a URL and no separating space — e.g. '**PR opened: https://.../pull/123**' —
greedily pulled the closing '**' into the href, producing a broken link and
an unterminated bold run. Exclude '*' from both URL character classes; '_'
and '~' (which can appear in real paths) are preserved.

apps/desktop/src/components/assistant-ui/markdown-text.test.ts

@@ -172,4 +172,33 @@ describe('preprocessMarkdown', () => {
       '<https://www.getyourguide.com/en-gb/san-juan-puerto-rico-l355/san-juan-old-san-juan-sunset-cruise-with-drinks-transfer-t405191/>'
     )
   })
+
+  it('does not swallow trailing emphasis asterisks into an autolinked url', () => {
+    const input = '**PR opened: https://github.com/NousResearch/hermes-agent/pull/12345**'
+
+    const output = preprocessMarkdown(input)
+
+    // The URL is autolinked WITHOUT the trailing `**` glued into the href,
+    // and the bold emphasis run stays intact so it renders as bold + a link.
+    expect(output).toContain('<https://github.com/NousResearch/hermes-agent/pull/12345>')
+    expect(output).not.toContain('pull/12345**>')
+    expect(output).not.toContain('12345*')
+  })
+
+  it('stops an autolinked url at mid-string bold markers', () => {
+    const input = 'See https://github.com/foo/bar**bold** for details.'
+
+    const output = preprocessMarkdown(input)
+
+    expect(output).toContain('<https://github.com/foo/bar>')
+    expect(output).toContain('**bold**')
+  })
+
+  it('keeps underscores and tildes inside autolinked url paths', () => {
+    const input = 'Docs at https://example.com/a_b/c~d/page'
+
+    const output = preprocessMarkdown(input)
+
+    expect(output).toContain('<https://example.com/a_b/c~d/page>')
+  })
 })