feat: add GitHub repository dashboard with Prometheus metrics

ghtracker authenticates as a GitHub App and scans a configured list of repositories on a schedule. It serves a dashboard, a JSON state endpoint, a health probe and Prometheus metrics.

The dashboard lists only items that need attention: failing workflows, pull requests that wait too long or fail their checks, stale issues and projects that failed to scan. It has search, dynamic filters and a button that rescans on demand. The Vue app is embedded in the Go binary.

The client protects the GitHub rate limit with conditional requests, a request reserve and Retry-After handling.

src/components/FleetStrip.vue

@@ -0,0 +1,52 @@
+<script setup lang="ts">
+import { Tooltip, TooltipContent, TooltipProvider, TooltipTrigger } from '@/components/ui/tooltip'
+import type { Repo } from '@/lib/types'
+import type { RepoCounts } from '@/stores/tracker'
+
+defineProps<{
+  repos: Repo[]
+  counts: Map<string, RepoCounts>
+  focused: string | null
+  matching: Set<string>
+}>()
+defineEmits<{ select: [fullName: string] }>()
+
+const SEGMENT = { crit: 'bg-crit', warn: 'bg-warn', ok: 'bg-ok/30 hover:bg-ok/60' } as const
+
+function summary(c: RepoCounts | undefined): string {
+  if (!c) return 'healthy'
+  const parts = []
+  if (c.crit) parts.push(`${c.crit} critical`)
+  if (c.warn) parts.push(`${c.warn} ${c.warn === 1 ? 'warning' : 'warnings'}`)
+  return parts.join(' · ')
+}
+</script>
+
+<template>
+  <TooltipProvider :delay-duration="80">
+    <div class="flex gap-1" role="group" aria-label="Project health" data-test="strip">
+      <Tooltip v-for="repo in repos" :key="repo.fullName">
+        <TooltipTrigger as-child>
+          <button
+            type="button"
+            :aria-label="`${repo.fullName}: ${summary(counts.get(repo.fullName))}`"
+            :aria-pressed="focused === repo.fullName"
+            class="h-14 min-w-0 flex-1 rounded-[3px] transition-colors focus-visible:outline-offset-1"
+            :class="[
+              SEGMENT[repo.health],
+              focused === repo.fullName
+                ? 'ring-foreground ring-2 ring-offset-2 ring-offset-background'
+                : '',
+            ]"
+            data-test="segment"
+            @click="$emit('select', repo.fullName)"
+          />
+        </TooltipTrigger>
+        <TooltipContent>
+          <p class="font-medium">{{ repo.fullName }}</p>
+          <p class="opacity-80">{{ summary(counts.get(repo.fullName)) }}</p>
+        </TooltipContent>
+      </Tooltip>
+    </div>
+  </TooltipProvider>
+</template>