feat: route files, other schemes, and batches instead of dropping them

[TerrifiedBug]

Setting Browseroute as the default browser makes LaunchServices bind public.html to it, so Finder hands .html files over as file:// URLs — and Router.route silently dropped every non-http(s) scheme. Nothing opened.

Changes

• Nothing is dropped. Router.route(_ urls: [URL]) forwards every URL it is handed. Rules still decide http/https only; local files, unknown schemes, and paused routing go to the Default catch-all.
• One catch-all definition. RoutingConfig.catchAllBrowserId (default → first browser → Safari) replaces the expression that was duplicated across CompiledRules and Router.
• Batches. URLs are grouped by destination in arrival order, so a multi-file open reaches each browser in a single NSWorkspace.open call and tab order matches the Finder selection.
• Fallback on open failure. BrowserLauncher.open takes [URL] and falls back to the catch-all when the chosen browser is missing or cannot open the items, with a notification either way.
• URLLabel. One label for logs, notifications and the popover caption: index.html, example.com, mailto:x@y.z, 3 items.
• Open With. Info.plist declares Alternate-rank viewer types for svg, plain-text, js, css, xml, gif, jpeg, png, webp, avif and pdf. The existing html/xhtml entry is untouched, so no default is stolen.
• Version bumped to 0.2.0; README + CHANGELOG updated.

Verification

make check: 0 SwiftLint violations, 22 tests pass. Installed the debug build to /Applications, re-registered with lsregister -f, and exercised the live app (Default catch-all = Chrome, Island rule on *.microsoft.com):

Case	Result
Local .html (the reported break)	Routing br-test.html -> com.google.Chrome, Chrome tab file:///private/tmp/br-test.html
Three files at once	one log line Routing 3 items -> com.google.Chrome, three tabs in arrival order
Mixed https + file	Routing br-test.html -> com.google.Chrome and Routing www.microsoft.com -> io.island.Island; Island got only the link
mailto:x@y.z	Routing mailto:x@y.z -> com.google.Chrome, no error, not dropped
Open With	Browseroute listed for all 13 declared extensions via NSWorkspace.urlsForApplications(toOpen:); png/pdf still default to Preview, txt/js to Sublime, html still to Browseroute
Missing browser	throwaway test: opened == true, destination == com.apple.Safari, Browser com.nonexistent.app not found — opened in Safari, file really opened in Safari
Routing paused	both items → catch-all, log lines prefixed Paused
Popover caption	live screenshot reads 2 items → Google Chrome

New unit tests cover the file-URL catch-all (a path must not be mistaken for a host), catchAllBrowserId precedence, and URLLabel.

Note: macOS delivers open <url> <file> as two separate application(_:open:) calls, so a mixed selection yields one group per call. Grouping only ever merges what arrives together, which is what tab ordering needs.