fix: route sign-in links by what can actually catch the callback

`isAnthropicSignInUrl` made the container the default action for every
Anthropic sign-in link, justified by "the host has nothing to catch it
with". That was wrong in both directions. The host does have something --
the auth bridge -- and the container side is not a general browser at all
but Playwright's dashboard, whose packages and chromium are deliberately
not baked into the image. So the default pointed at the one path that is
uninstalled on a fresh project, on every platform, while the path that
works sat behind a switch.

The decision now lives in `useSignInOpenTarget`: a live auth bridge picks
the host, otherwise a container that can actually launch a browser picks
the container, otherwise the host. It resolves at mount rather than when a
URL arrives, so the buttons do not swap under a moving mouse, and it
re-decides on `auth-bridge-changed` so flipping the switch during a
hanging login takes effect. A bridge with port conflicts reads as not
live; an empty `active_ports` does not, since there is nothing to bridge
until the CLI binds its listener and that races the URL.

Both buttons still render either way -- this changes which one leads.
`sanitizeRelayUrl` is byte-for-byte unchanged, so the embedded copy in
web_terminal/terminal.html needs no matching edit.

The host "Open" path also failed silently: `dismissUrlPrompt()` ran before
`openUrl`, so the toast vanished and a rejected promise reached only the
devtools console. Dismissal now happens on success only, leaving "In
container" one click away after a failure, and the error surfaces through
the same toast the container path already used. On Linux this catch will
not fire for the common case -- `xdg-open` routinely exits 0 having done
nothing -- so it complements the AppImage environment fix rather than
replacing it.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

app/src/components/projects/home/BrowserTab.tsx

@@ -23,6 +23,7 @@ import {
   setBrowserViewMatchWindow,
   setBrowserViewPopoutAlwaysOnTop,
 } from "../../../lib/tauri-commands";
+import { isBrowserViewUsable } from "../../../lib/browserViewSupport";
 import { useAppState } from "../../../store/appState";
 import OpenPageDialog from "./OpenPageDialog";
 import AccordionSection from "../../ui/AccordionSection";
@@ -338,7 +339,7 @@ export default function BrowserTab({ project, active }: Props) {
   // Prefer the probe: it is the fresher of the two, and it is the one that
   // reflects an install that just finished.
   const probed = detection ?? status.detection;
-  const ready = isUsable(probed);
+  const ready = isBrowserViewUsable(probed);
   // Mirrors Rust `PlaywrightDetection::needs_browser`: the Chrome channel is an
   // apt package, so it never shows up in `browsers`, and a container that has
   // it is not missing a browser.
@@ -539,11 +540,6 @@ export default function BrowserTab({ project, active }: Props) {
   );
 }
 
-/** Mirrors Rust `PlaywrightDetection::is_usable`. */
-function isUsable(d: PlaywrightDetection | null): boolean {
-  return d !== null && d.playwright_version !== null && d.has_bind && d.cli_entry !== null;
-}
-
 /**
  * Mirrors Rust `PlaywrightDetection::revision_skew`.
  *
@@ -627,7 +623,7 @@ function Setup({
   onInstall: (which: Exclude<SetupJob, null>) => void;
 }) {
   const busy = job !== null;
-  const havePackages = isUsable(detection);
+  const havePackages = isBrowserViewUsable(detection);
   const missing = missingParts(detection);
   const browsers = detection?.browsers ?? [];
   const chrome = detection?.chrome_channel ?? null;