feat(cli): add --dump markdown output mode (#54) (#78)

Surfaces the existing LP.getMarkdown CDP machinery as a CLI flag so
text-pipeline users (LLM agents, scrapers feeding markdown to other
tools) don't need a separate HTML-to-markdown converter step.

  obscura fetch --dump markdown 'https://example.com'

Layout:
- crates/obscura-js/src/markdown.rs holds HTML_TO_MARKDOWN_JS as a
  pub const so every layer can share the same DOM-walker. obscura-js
  is at the bottom of the dep DAG (obscura-browser -> obscura-js,
  obscura-cdp -> obscura-js, obscura-cli -> obscura-js) so a single
  source of truth works without a circular dependency.
- crates/obscura-browser/src/lib.rs re-exports it for ergonomics.
- crates/obscura-cdp/src/domains/lp.rs drops its inline duplicate
  and calls the shared const.
- crates/obscura-cli/src/main.rs adds the `Markdown` DumpFormat
  variant + dump_markdown(&mut Page) which page.evaluate's the
  shared script and prints the result.

Net diff: a new 75-line markdown.rs, a 70+ line deletion in lp.rs
that's reborn as 3 lines, and ~10 lines added across the other four
files. No behavior change for `--dump html|text|links`, and
LP.getMarkdown over CDP keeps the exact same JSON shape.

Four new unit tests in obscura-js cover headings, inline emphasis +
links, ordered/unordered lists, and that <script> / <style> contents
do not leak into the output.

Generated by Ora Studio
Vibe coded by ousamabenyounes

Co-authored-by: Ora Studio <[email protected]>

crates/obscura-cdp/src/domains/lp.rs

@@ -1,3 +1,4 @@
+use obscura_browser::HTML_TO_MARKDOWN_JS;
 use serde_json::{json, Value};
 
 use crate::dispatch::CdpContext;
@@ -11,72 +12,7 @@ pub async fn handle(
     match method {
         "getMarkdown" => {
             let page = ctx.get_session_page_mut(session_id).ok_or("No page")?;
-            let code = r#"
-(function() {
-    function toMd(el, depth) {
-        if (!el) return '';
-        var out = '';
-        if (el.nodeType === 3) return el.textContent || '';
-        if (el.nodeType !== 1) return '';
-        var tag = (el.tagName || '').toLowerCase();
-        var children = '';
-        var cn = el.childNodes || [];
-        for (var i = 0; i < cn.length; i++) children += toMd(cn[i], depth);
-        children = children.replace(/\n{3,}/g, '\n\n');
-        switch(tag) {
-            case 'h1': return '\n# ' + children.trim() + '\n\n';
-            case 'h2': return '\n## ' + children.trim() + '\n\n';
-            case 'h3': return '\n### ' + children.trim() + '\n\n';
-            case 'h4': return '\n#### ' + children.trim() + '\n\n';
-            case 'h5': return '\n##### ' + children.trim() + '\n\n';
-            case 'h6': return '\n###### ' + children.trim() + '\n\n';
-            case 'p': return '\n' + children.trim() + '\n\n';
-            case 'br': return '\n';
-            case 'hr': return '\n---\n\n';
-            case 'strong': case 'b': return '**' + children + '**';
-            case 'em': case 'i': return '*' + children + '*';
-            case 'code': return '`' + children + '`';
-            case 'pre': return '\n```\n' + children + '\n```\n\n';
-            case 'blockquote': return '\n> ' + children.trim().replace(/\n/g, '\n> ') + '\n\n';
-            case 'a':
-                var href = el.getAttribute('href') || '';
-                if (href && children.trim()) return '[' + children.trim() + '](' + href + ')';
-                return children;
-            case 'img':
-                var src = el.getAttribute('src') || '';
-                var alt = el.getAttribute('alt') || '';
-                return '![' + alt + '](' + src + ')';
-            case 'ul': case 'ol':
-                return '\n' + children + '\n';
-            case 'li':
-                var parent = el.parentNode;
-                var isOrdered = parent && parent.tagName && parent.tagName.toLowerCase() === 'ol';
-                var bullet = isOrdered ? '1. ' : '- ';
-                return bullet + children.trim() + '\n';
-            case 'table': return '\n' + children + '\n';
-            case 'thead': case 'tbody': case 'tfoot': return children;
-            case 'tr':
-                var cells = [];
-                var tds = el.childNodes || [];
-                for (var j = 0; j < tds.length; j++) {
-                    if (tds[j].nodeType === 1) cells.push(toMd(tds[j], depth).trim());
-                }
-                return '| ' + cells.join(' | ') + ' |\n';
-            case 'th': case 'td': return children;
-            case 'script': case 'style': case 'noscript': case 'link': case 'meta': return '';
-            case 'div': case 'section': case 'article': case 'main': case 'aside': case 'nav': case 'header': case 'footer':
-                return '\n' + children;
-            case 'span': return children;
-            default: return children;
-        }
-    }
-    var body = document.body || document.documentElement;
-    var md = toMd(body, 0);
-    md = md.replace(/\n{3,}/g, '\n\n').trim();
-    return md;
-})()
-"#;
-            let result = page.evaluate(code);
+            let result = page.evaluate(HTML_TO_MARKDOWN_JS);
             let markdown = result.as_str().unwrap_or("").to_string();
             Ok(json!({ "markdown": markdown }))
         }