feat: local content-mining platform for YouTube creator scraping

Scraper de canales de YouTube hacia notas Markdown para base de conocimiento
(Obsidian-ready), con plataforma web local.

Engine + CLI (Workstream A):
- Modular pipeline: discover/extract/parse/chapters/render/store + ratelimit
- SQLite store con migración idempotente: FTS5 (transcript search), columnas
  de metadata enriquecida, tablas cookies_meta y scrape_jobs
- Módulos: segments, cookies (Netscape vault), export (json/csv/srt/html),
  analysis (word freq/timeline/wordcloud), monitor (watch loop), pipeline
- CLI Click group: search, export, audio, channels, watch, analyze, re-render
- Fix del bug de scoping de cookies en cli.py

Webapp local (Workstream B):
- FastAPI backend: dashboard, channels, videos facetado, transcript, search
  FTS, analysis, scrape jobs con SSE, cookies drag-and-drop, exports,
  folders (abrir en OS), tools (re-render, formato)
- SPA no-build (Alpine.js + Tailwind + Chart.js por CDN): 9 vistas, tema
  dark command-center con acento rojo→rosa, cookie vault drag-drop,
  consola de scrapeo con progreso live vía SSE

Launcher + subagentes (Workstream C):
- start-server.bat / stop-server.bat con auto port-scan + browser open
- .opencode/agent/webapp-builder.md + .opencode/goals/webapp-build.md

Tests: 38 pytest verdes. Sin funcionalidad de IA (enfoque data-mining).

src/yt_scraper/render.py

@@ -0,0 +1,72 @@
+from __future__ import annotations
+
+from datetime import datetime, timezone
+from pathlib import Path
+
+from jinja2 import Environment, FileSystemLoader, select_autoescape
+
+from .chapters import Section
+
+
+def format_timestamp(seconds: float) -> str:
+    total = int(seconds)
+    hours, remainder = divmod(total, 3600)
+    minutes, secs = divmod(remainder, 60)
+    if hours > 0:
+        return f"{hours:02d}:{minutes:02d}:{secs:02d}"
+    return f"{minutes:02d}:{secs:02d}"
+
+
+def quote_yaml(value: str | None) -> str:
+    if value is None:
+        return '""'
+    needs_quote = any(c in value for c in [':', '#', '{', '}', '[', ']', ',', '&', '*', '!', '|', '>', "'", '"', '%', '@', '`', '\n'])
+    if needs_quote:
+        escaped = value.replace('"', '\\"')
+        return f'"{escaped}"'
+    return value
+
+
+def to_json(value) -> str:
+    import json
+    return json.dumps(value, ensure_ascii=False)
+
+
+def _make_env(template_dir: Path) -> Environment:
+    env = Environment(
+        loader=FileSystemLoader(str(template_dir)),
+        autoescape=select_autoescape(disabled_extensions=("j2", "txt")),
+        trim_blocks=True,
+        lstrip_blocks=True,
+    )
+    env.filters["format_timestamp"] = format_timestamp
+    env.filters["quote_yaml"] = quote_yaml
+    env.filters["to_json"] = to_json
+    return env
+
+
+def render_markdown(
+    template_path: str | Path,
+    output_dir: str | Path,
+    filename_stem: str,
+    context: dict,
+) -> Path:
+    tpl_path = Path(template_path).resolve()
+    env = _make_env(tpl_path.parent)
+    template = env.get_template(tpl_path.name)
+    rendered = template.render(**context)
+
+    out_dir = Path(output_dir)
+    out_dir.mkdir(parents=True, exist_ok=True)
+    out_file = out_dir / f"{filename_stem}.md"
+    out_file.write_text(rendered, encoding="utf-8")
+    return out_file
+
+
+def build_filename_stem(upload_date: str | None, title: str, template: str = "{upload_date}_{slug}") -> str:
+    from slugify import slugify
+    date_part = upload_date or "unknown-date"
+    slug = slugify(title, max_length=60) or "untitled"
+    stem = template.format(upload_date=date_part, slug=slug, title=title)
+    safe = "".join(c for c in stem if c not in r'\/:*?"<>|')
+    return safe.strip().strip(".")