Initial commit: NexusOS project + desktop theme baseline

Captures the known-good state after theme consolidation and
consistency reconciliation:
- NexusOS GTK/xfwm4/icon theme assets (assets/themes, management/Mint-Y-Nexus)
- Tightened right-click menus, visible separators, no menu icons
- assets/themes/install-theme.sh: idempotent restore of all wiring
  (symlinks, xfconf xsettings+xfwm4, GTK 3/4 settings.ini)
- .gitignore excludes venv/ollama/models/runtime/db

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

interface/web/src/Markdown.jsx

@@ -0,0 +1,143 @@
+export function Markdown({ content }) {
+  if (!content) return null;
+
+  const blocks = [];
+  const codeBlockRe = /```(\w*)\n?([\s\S]*?)```/g;
+  let last = 0;
+  let match;
+
+  while ((match = codeBlockRe.exec(content)) !== null) {
+    if (match.index > last) {
+      blocks.push({ type: "text", value: content.slice(last, match.index) });
+    }
+    blocks.push({ type: "code", lang: match[1], value: match[2] });
+    last = match.index + match[0].length;
+  }
+  if (last < content.length) {
+    blocks.push({ type: "text", value: content.slice(last) });
+  }
+
+  return (
+    <div style={{ lineHeight: "1.6" }}>
+      {blocks.map((block, i) =>
+        block.type === "code" ? (
+          <pre key={i} style={{
+            background: "#0d0d0d",
+            border: "1px solid #2a2a2a",
+            borderRadius: "6px",
+            padding: "0.75rem 1rem",
+            overflowX: "auto",
+            fontSize: "0.85rem",
+            lineHeight: "1.5",
+            margin: "0.5rem 0",
+            fontFamily: "monospace",
+          }}>
+            <code>{block.value.trimEnd()}</code>
+          </pre>
+        ) : (
+          <TextBlock key={i} text={block.value} />
+        )
+      )}
+    </div>
+  );
+}
+
+function TextBlock({ text }) {
+  const lines = text.split("\n");
+  const elements = [];
+  let i = 0;
+
+  while (i < lines.length) {
+    const line = lines[i];
+
+    // Heading
+    const hMatch = line.match(/^(#{1,3})\s+(.+)/);
+    if (hMatch) {
+      const level = hMatch[1].length;
+      const sizes = { 1: "1.2rem", 2: "1.05rem", 3: "0.95rem" };
+      elements.push(
+        <div key={i} style={{ fontWeight: "700", fontSize: sizes[level], margin: "0.6rem 0 0.2rem", color: "#fff" }}>
+          {inlineMarkdown(hMatch[2])}
+        </div>
+      );
+      i++;
+      continue;
+    }
+
+    // Unordered list
+    if (/^[-*]\s+/.test(line)) {
+      const items = [];
+      while (i < lines.length && /^[-*]\s+/.test(lines[i])) {
+        items.push(<li key={i}>{inlineMarkdown(lines[i].replace(/^[-*]\s+/, ""))}</li>);
+        i++;
+      }
+      elements.push(<ul key={`ul-${i}`} style={{ paddingLeft: "1.25rem", margin: "0.25rem 0" }}>{items}</ul>);
+      continue;
+    }
+
+    // Ordered list
+    if (/^\d+\.\s+/.test(line)) {
+      const items = [];
+      while (i < lines.length && /^\d+\.\s+/.test(lines[i])) {
+        items.push(<li key={i}>{inlineMarkdown(lines[i].replace(/^\d+\.\s+/, ""))}</li>);
+        i++;
+      }
+      elements.push(<ol key={`ol-${i}`} style={{ paddingLeft: "1.25rem", margin: "0.25rem 0" }}>{items}</ol>);
+      continue;
+    }
+
+    // Horizontal rule
+    if (/^---+$/.test(line.trim())) {
+      elements.push(<hr key={i} style={{ border: "none", borderTop: "1px solid #333", margin: "0.5rem 0" }} />);
+      i++;
+      continue;
+    }
+
+    // Empty line → small gap
+    if (line.trim() === "") {
+      elements.push(<div key={i} style={{ height: "0.4rem" }} />);
+      i++;
+      continue;
+    }
+
+    // Regular paragraph line
+    elements.push(<div key={i}>{inlineMarkdown(line)}</div>);
+    i++;
+  }
+
+  return <>{elements}</>;
+}
+
+function inlineMarkdown(text) {
+  const parts = [];
+  const re = /(\*\*(.+?)\*\*|\*(.+?)\*|`([^`]+)`)/g;
+  let last = 0;
+  let m;
+
+  while ((m = re.exec(text)) !== null) {
+    if (m.index > last) parts.push(text.slice(last, m.index));
+
+    if (m[2] !== undefined) {
+      parts.push(<strong key={m.index}>{m[2]}</strong>);
+    } else if (m[3] !== undefined) {
+      parts.push(<em key={m.index}>{m[3]}</em>);
+    } else if (m[4] !== undefined) {
+      parts.push(
+        <code key={m.index} style={{
+          background: "#1e1e1e",
+          border: "1px solid #333",
+          borderRadius: "3px",
+          padding: "0.1rem 0.35rem",
+          fontSize: "0.85em",
+          fontFamily: "monospace",
+        }}>
+          {m[4]}
+        </code>
+      );
+    }
+    last = m.index + m[0].length;
+  }
+
+  if (last < text.length) parts.push(text.slice(last));
+  return parts.length === 1 && typeof parts[0] === "string" ? parts[0] : parts;
+}