v1.6.0 Auto-Mode cost control, YouTube subtitles, header auth, crawl fix

What's Changed

• [SCR-383] Auto-Mode (--mode auto / --max-cost) support by @kostas-jakeliunas-sb in #26
• [SCR-577] API parity: youtube-subtitles command, google --pages and --search-type ads by @sahilsunny in #31
• Update scrapingbee-cli package to support Header based Authorization by @sahilsunny in #32
• Fix discovery crawls saving zero pages on Scrapy ≥ 2.13 by @sahilsunny in #33
• SCR-712: Canonical agent skill — router SKILL.md, CLI/MCP routing, generated derivatives by @sahilsunny in #34
• chore(release): set 1.6.0 date to 2026-09-11 by @sahilsunny in #35

Full Changelog: v1.5.1...v1.6.0