feat: project overview + timeline + docs center

- services/task_project_linker.py: task<->project mapping (title keywords + workspace_path)
- routes/pages.py: /timeline, /docs, /docs/<path>, enhanced /projects/<name> and /tasks/<id>
- templates: timeline.html, docs.html, doc_view.html (new), project_detail.html + task_detail.html (overhauled)
- config.py: DOCS_DIRS + ProjectConfig color
- base.html: Timeline + Docs nav links

templates/doc_view.html

@@ -0,0 +1,81 @@
+{% extends "base.html" %}
+
+{% block title %}{{ title }} - Docs{% endblock %}
+
+{% block content %}
+<p class="text-small text-muted">
+    <a href="/docs">Docs</a> &gt; {{ rel_path }}
+</p>
+
+<h2>📄 {{ title }}</h2>
+
+<div class="card">
+    {% if rendered_html %}
+        <div class="markdown-body">
+            {{ rendered_html|safe }}
+        </div>
+    {% else %}
+        <pre>{{ raw }}</pre>
+    {% endif %}
+</div>
+
+<p class="mt-20">
+    <a href="/docs" class="btn">← Back to Docs</a>
+</p>
+
+<style>
+.markdown-body h1, .markdown-body h2, .markdown-body h3, .markdown-body h4 {
+    color: #fff;
+    margin-top: 20px;
+    margin-bottom: 10px;
+    border-bottom: 1px solid #3a3a3a;
+    padding-bottom: 5px;
+}
+.markdown-body h1 { font-size: 22px; }
+.markdown-body h2 { font-size: 18px; }
+.markdown-body h3 { font-size: 16px; }
+.markdown-body p { margin: 10px 0; }
+.markdown-body code {
+    background: #1a1a1a;
+    padding: 2px 5px;
+    border-radius: 3px;
+    font-size: 13px;
+    color: #ff9e4a;
+}
+.markdown-body pre {
+    background: #1a1a1a;
+    border: 1px solid #3a3a3a;
+    padding: 10px;
+    border-radius: 3px;
+    overflow-x: auto;
+    margin: 10px 0;
+}
+.markdown-body pre code {
+    background: transparent;
+    padding: 0;
+    color: #e0e0e0;
+}
+.markdown-body ul, .markdown-body ol {
+    margin-left: 25px;
+    margin-top: 5px;
+    margin-bottom: 10px;
+}
+.markdown-body table {
+    width: 100%;
+    border-collapse: collapse;
+    margin: 10px 0;
+}
+.markdown-body th, .markdown-body td {
+    padding: 6px 10px;
+    border: 1px solid #3a3a3a;
+}
+.markdown-body th { background: #333; }
+.markdown-body blockquote {
+    border-left: 3px solid #4a9eff;
+    padding-left: 15px;
+    margin: 10px 0;
+    color: #aaa;
+}
+.markdown-body a { color: #4a9eff; }
+</style>
+{% endblock %}