Add nested posts UI (#5)

## Summary
- Cut hunt, question, submission, voting, hiding, and profile flows over to unified posts
- Render nested replies with permission-aware inline Reply/Edit controls and edited markers
- Add post profile queries and the author index migration they depend on

Co-authored-by: codegirl-007 <s.raide@gmail.com>

templates/partials/_list.html

@@ -1,6 +1,6 @@
 {{define "leaderboard"}}
 <ol id="leaderboard" class="board" start="1">
-  {{if not .Questions}}
+  {{if not .Posts}}
     <li class="empty">
       {{if eq .Date .Today}}
         <p class="empty-kicker">Queue empty</p>
@@ -10,20 +10,20 @@
       {{end}}
     </li>
   {{else}}
-    {{range $i, $q := .Questions}}
+    {{range $i, $post := .Posts}}
       <li class="row">
         <span class="rank" aria-hidden="true">{{rank $i}}</span>
-        {{template "vote" (voteCtx $.User $.CSRF "list" $.Date $q)}}
+        {{template "vote" (voteCtx $.User $.CSRF "list" $.Date $post)}}
         <div class="row-body">
-          <a class="q-title" href="/questions/{{$q.ID}}">{{$q.Title}}</a>
+          <a class="q-title" href="/questions/{{$post.ID}}">{{$post.Title}}</a>
           <p class="meta">
-            <span>{{$q.AuthorName}}</span>
-            {{if $q.City}}<span class="dot" aria-hidden="true">·</span><span>{{$q.City}}</span>{{end}}
-            {{if $q.Answered}}<span class="badge">Answered</span>{{end}}
+            <span>{{$post.AuthorName}}</span>
+            {{if $post.City}}<span class="dot" aria-hidden="true">·</span><span>{{$post.City}}</span>{{end}}
+            {{if $post.Answered}}<span class="badge">Answered</span>{{end}}
           </p>
           {{if isAdmin $.User}}
-            <form class="inline-hide" method="post" action="/questions/{{$q.ID}}/hide"
-              hx-post="/questions/{{$q.ID}}/hide" hx-target="#leaderboard" hx-swap="outerHTML">
+            <form class="inline-hide" method="post" action="/questions/{{$post.ID}}/hide"
+              hx-post="/questions/{{$post.ID}}/hide" hx-target="#leaderboard" hx-swap="outerHTML">
               <input type="hidden" name="_csrf" value="{{$.CSRF}}">
               <input type="hidden" name="view" value="list">
               <button type="submit" class="linkish">Hide</button>