fix: the crawler and the Chrome guard keep to the site's port

Fetcher.Allowed and Key, the rendered comparison and the Chrome request
guard accept an address only on the site's effective port (explicit,
else 443 for https and 80 for http), so page code cannot make headless
Chrome reach other services on the site host's address and a link to
another port is not reported as a page of the site.

README.md

@@ -253,7 +253,7 @@ A crawl is a conga job (`golem15.seo.crawl`, one attempt) started from **Start c
 
 **Raw HTML against the CMS.** The server-rendered HTML is checked against the record behind the page (`content_js` with `details.check: cms`): the record's title must appear in an H1, the text must reach half of the record's word count, and the record's primary parent (the breadcrumb link) must be linked. The comparison with the JavaScript-rendered page is `details.check: rendered` (next section); without a Chrome path every crawl records it as skipped (P6 and `seo_get_crawl` say so).
 
-**Rendered comparison.** When `golem15.seo.crawl_chrome_path` names a Chrome or Chromium binary the operator installed on the server (none is installed by default), the crawler renders the first `golem15.seo.crawl_render_max` pages (default 200, in crawl order, so the home page and the top-level pages come first) in headless Chrome through `github.com/chromedp/chromedp`, right after each page's raw fetch, and compares the DOM after JavaScript with the raw HTML: same-host links, an H1, or at least 50 words and 20 % more text that appear only after JavaScript are one `content_js` finding with `details.check: rendered` and `details.what` naming them (up to five links). The browser is held to the crawler's limits: before Chrome starts, the site host and its `www` twin are resolved and every address checked like the crawler's dial guard (`fetchguard.IsPrivateAddr`; a private address refuses unless `golem15.seo.crawl_trusted` is on), and Chrome is pinned to those addresses through `--host-resolver-rules` while every other host resolves to nothing; every request is intercepted and continued only when it is https (http only in trusted mode) to the site host or its twin, or a `data:`/`blob:` URL, so third-party scripts, fonts, analytics and metadata addresses are never loaded. Each crawl gets a fresh temporary profile, removed when the crawl ends, with no cookies, credentials or extensions and downloads denied; one tab renders at a time, at most 5 s to open the tab (`crawl.TabOpenTimeout`) and 20 s for the page under one deadline, so a hung Chrome cannot stall the crawl, the DOM is capped at 5 MiB, Chrome's own sandbox stays on, and Chrome is closed when the crawl finishes, fails or is cancelled. The path is config only (or `SUMMER_GOLEM15__SEO__CRAWL_CHROME_PATH`), never a setting or MCP value. The crawl records `render_status` `done` with the pages compared, `skipped` without a path, or `failed` with the reason (a relative path or one that is not an executable file, a private address, Chrome not starting, a page that cannot be rendered); a renderer failure never fails the crawl, and P6, `GET /_seo/api/v1/crawls/{id}` and `seo_get_crawl` (`render {status, pages, note, message}`) say which.
+**Rendered comparison.** When `golem15.seo.crawl_chrome_path` names a Chrome or Chromium binary the operator installed on the server (none is installed by default), the crawler renders the first `golem15.seo.crawl_render_max` pages (default 200, in crawl order, so the home page and the top-level pages come first) in headless Chrome through `github.com/chromedp/chromedp`, right after each page's raw fetch, and compares the DOM after JavaScript with the raw HTML: same-host links, an H1, or at least 50 words and 20 % more text that appear only after JavaScript are one `content_js` finding with `details.check: rendered` and `details.what` naming them (up to five links). The browser is held to the crawler's limits: before Chrome starts, the site host and its `www` twin are resolved and every address checked like the crawler's dial guard (`fetchguard.IsPrivateAddr`; a private address refuses unless `golem15.seo.crawl_trusted` is on), and Chrome is pinned to those addresses through `--host-resolver-rules` while every other host resolves to nothing; every request is intercepted and continued only when it is https (http only in trusted mode) to the site host or its twin on the site's own port (the port of `golem15.seo.site_url`, else 443 for https and 80 for http), or a `data:`/`blob:` URL, so page code cannot reach other services on the site host's address, so third-party scripts, fonts, analytics and metadata addresses are never loaded. Each crawl gets a fresh temporary profile, removed when the crawl ends, with no cookies, credentials or extensions and downloads denied; one tab renders at a time, at most 5 s to open the tab (`crawl.TabOpenTimeout`) and 20 s for the page under one deadline, so a hung Chrome cannot stall the crawl, the DOM is capped at 5 MiB, Chrome's own sandbox stays on, and Chrome is closed when the crawl finishes, fails or is cancelled. The path is config only (or `SUMMER_GOLEM15__SEO__CRAWL_CHROME_PATH`), never a setting or MCP value. The crawl records `render_status` `done` with the pages compared, `skipped` without a path, or `failed` with the reason (a relative path or one that is not an executable file, a private address, Chrome not starting, a page that cannot be rendered); a renderer failure never fails the crawl, and P6, `GET /_seo/api/v1/crawls/{id}` and `seo_get_crawl` (`render {status, pages, note, message}`) say which.
 
 **Fix routes.** An issue a CMS value fixes names its tool: `seo_set_url_seo` (titles, descriptions, canonicals, sitemap membership of a record, structured data), `seo_update_robots`, `seo_create_redirect` (a missing page, a page that answers an error), `seo_create_page` (a page missing from the registry), `seo_update_settings` (publisher and site nodes), `sitemap_update_settings` (a listed noindex address without a CMS record, an Additional address of the sitemap: remove it there; `details.extra` is true, and without the sitemap plugin the issue is `fix: code` naming the sitemap's address list), or the content type's own tool from `pact.ContentDescriptor.Tools` when the problem sits in the record's content: H1 findings prefer `Tools[headings]`, image alt text `Tools[image_alt]`, other content findings `Tools[edit]` (the registry pages name `seo_update_page`). A finding of the site's template code, or of content whose type names no fitting tool, is `fix: code` with `details.what` naming the element to change. No issue has neither.