fix(umami): align URL stats with share API filters

[yCENzh]

Summary

• Fixed getPageStatsByUrl to parse a full URL into the actual Umami stats filters (path + hostname) instead of sending the ignored url query parameter.
• Added hostname support to stats query parameters and expanded MetricType to match the currently documented Umami v2 metric types (entry, exit, query, channel, domain, hostname, distinctId, etc.).
• Updated tests and README to document the behavior discovered by checking the official cloud share page and the self-hosted share page.
• Addressed Devin Review by adding the missing query metric type and widening metric values to string | null, matching observed self-hosted type=query responses.

Review & Testing Checklist for Human

• Verify getPageStatsByUrl('https://your-domain/path?query=...') returns page-specific stats on your own Umami share link, especially when one website tracks multiple hostnames.
• Confirm callers that used options.path with getPageStatsByUrl do not rely on overriding the parsed path; the method now intentionally prioritizes the URL-derived path/hostname.
• Run a real integration check with both provided share URLs and compare getPageStatsByUrl against the same path in the Umami UI.

Notes

• Verified against the provided pages: official cloud.umami.is/analytics/us/share/pNrbzntfHm1jet1f and self-hosted umami.14131413.xyz/share/JsbYvsDKnsL both ignore url= on /stats; path= filters correctly, and hostname= further narrows multi-host self-hosted data.
• Verified type=query returns 200 on both provided endpoints; self-hosted can return { x: null, y: ... }.
• Local checks passed after the review fix: pnpm test, pnpm exec tsc --noEmit, pnpm build.