feat(18-01): chi v5 dependency, go:embed static assets, HTML layout and overview templates

- Add chi v5.2.5 to go.mod
- Vendor htmx v2.0.4 minified JS in pkg/web/static/
- Create go:embed directives for static/ and templates/
- Create layout.html with nav bar and Tailwind CDN
- Create overview.html with stat cards and findings table

pkg/web/templates/overview.html

@@ -0,0 +1,77 @@
+{{template "layout" .}}
+
+{{define "content"}}
+<!-- Stat cards -->
+<div class="grid grid-cols-1 sm:grid-cols-2 lg:grid-cols-4 gap-6 mb-8">
+    <div class="stat-card bg-white border border-gray-200">
+        <p class="text-sm font-medium text-gray-500">Total Keys Found</p>
+        <p class="mt-2 text-3xl font-bold text-gray-900">{{.TotalKeys}}</p>
+    </div>
+    <div class="stat-card bg-white border border-gray-200">
+        <p class="text-sm font-medium text-gray-500">Providers Loaded</p>
+        <p class="mt-2 text-3xl font-bold text-gray-900">{{.TotalProviders}}</p>
+    </div>
+    <div class="stat-card bg-white border border-gray-200">
+        <p class="text-sm font-medium text-gray-500">Recon Sources</p>
+        <p class="mt-2 text-3xl font-bold text-gray-900">{{.ReconSources}}</p>
+    </div>
+    <div class="stat-card bg-white border border-gray-200">
+        <p class="text-sm font-medium text-gray-500">Last Scan</p>
+        <p class="mt-2 text-xl font-bold text-gray-900">{{if .LastScan}}{{.LastScan}}{{else}}Never{{end}}</p>
+    </div>
+</div>
+
+<!-- Recent findings -->
+<div class="bg-white shadow-sm rounded-lg border border-gray-200">
+    <div class="px-6 py-4 border-b border-gray-200">
+        <h2 class="text-lg font-semibold text-gray-900">Recent Findings</h2>
+    </div>
+    {{if .RecentFindings}}
+    <div class="overflow-x-auto">
+        <table class="findings-table">
+            <thead>
+                <tr>
+                    <th>Provider</th>
+                    <th>Masked Key</th>
+                    <th>Source</th>
+                    <th>Confidence</th>
+                    <th>Verified</th>
+                    <th>Date</th>
+                </tr>
+            </thead>
+            <tbody>
+                {{range .RecentFindings}}
+                <tr>
+                    <td class="font-medium">{{.ProviderName}}</td>
+                    <td class="font-mono text-sm text-gray-600">{{.KeyMasked}}</td>
+                    <td class="text-sm text-gray-600">{{.SourcePath}}</td>
+                    <td>
+                        {{if eq .Confidence "high"}}
+                        <span class="inline-flex items-center px-2.5 py-0.5 rounded-full text-xs font-medium bg-green-100 text-green-800">High</span>
+                        {{else if eq .Confidence "medium"}}
+                        <span class="inline-flex items-center px-2.5 py-0.5 rounded-full text-xs font-medium bg-yellow-100 text-yellow-800">Medium</span>
+                        {{else}}
+                        <span class="inline-flex items-center px-2.5 py-0.5 rounded-full text-xs font-medium bg-gray-100 text-gray-800">{{.Confidence}}</span>
+                        {{end}}
+                    </td>
+                    <td>
+                        {{if .Verified}}
+                        <span class="text-green-600 font-medium">Live</span>
+                        {{else}}
+                        <span class="text-gray-400">-</span>
+                        {{end}}
+                    </td>
+                    <td class="text-sm text-gray-500">{{.CreatedAt.Format "2006-01-02 15:04"}}</td>
+                </tr>
+                {{end}}
+            </tbody>
+        </table>
+    </div>
+    {{else}}
+    <div class="px-6 py-12 text-center text-gray-500">
+        <p class="text-lg">No findings yet</p>
+        <p class="mt-1 text-sm">Run a scan to detect API keys</p>
+    </div>
+    {{end}}
+</div>
+{{end}}