feat(usage): open the TokenTracker dashboard from the usage monitor

The modal deliberately shows only a slice of the analytics; this hands off
to TokenTracker's own local dashboard for the rest. The worker starts
`tokentracker serve` on demand and returns the URL, the UI opens the browser.

Three things the spawn has to get right: port 7680 is not free on Windows
(Delivery Optimization holds [::]:7680) and serve does not fall back, so we
scan 7680-7689 with a dual-stack bind probe; --no-open because the CLI would
open the browser before the server answers; and the child is a cmd.exe shim,
so shutdown kills the process tree. --no-sync keeps our no-cloud-sync rule.

src/ClaudeDo.Localization/locales/en.json

@@ -535,6 +535,8 @@
       "analyticsStampFormat": "Analytics as of {0}",
       "analyticsNever": "Analytics not loaded yet",
       "analyticsRefresh": "Refresh analytics",
+      "openDashboard": "Open TokenTracker dashboard",
+      "openDashboardTip": "Starts TokenTracker's local dashboard (localhost only, no cloud sync) and opens it in your browser. The first start takes a few seconds.",
       "analyticsTotalsFormat": "{0} tokens · ${1}",
       "ttMissingTitle": "Token analytics need TokenTracker",
       "ttMissingBody": "TokenTracker (MIT) reads your local Claude transcripts and never sees prompts. ClaudeDo only calls its local export — it does not run `init`, installs no hooks and enables no cloud sync.",
@@ -750,7 +752,9 @@
       "thresholdSaveFailed": "Couldn't save the threshold: {0}",
       "installStarted": "Installing TokenTracker — watch the log strip for progress.",
       "installFailed": "Couldn't install TokenTracker: {0}",
-      "analyticsRefreshFailed": "Couldn't refresh the analytics: {0}"
+      "analyticsRefreshFailed": "Couldn't refresh the analytics: {0}",
+      "dashboardFailed": "Couldn't open the TokenTracker dashboard: {0}",
+      "dashboardUnavailable": "the local dashboard server did not start"
     },
     "filesTab": { "workerOffline": "Worker offline.", "noneBundled": "No default agents bundled.", "allPresent": "All default agents already present.", "restored": "Restored {0} default agent(s).", "restoreFailed": "Restore failed: {0}", "resetToDefault": "Reset to the bundled default." },
     "sessionSkillsTab": { "installed": "Installed: {0}", "installFailed": "Install failed: {0}", "updated": "Updated.", "updateFailed": "Update failed: {0}", "removed": "Removed.", "removeFailed": "Remove failed: {0}" },