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>

internal/web/profile.go

@@ -23,7 +23,7 @@ import (
 type profilePage struct {
 	page
 	States         []struct{ Code, Name string }
-	Questions      []store.RankedQuestion
+	Posts          []store.Post
 	QuestionsLabel string
 	UploadsEnabled bool
 	Error          string
@@ -255,16 +255,16 @@ func fitAvatar(img image.Image, maxDim int) image.Image {
 
 func (s *Server) renderProfile(w http.ResponseWriter, r *http.Request, u *store.User, errMsg, stateVal, emailVal string) {
 	var (
-		questions []store.RankedQuestion
-		label     string
-		err       error
+		posts []store.Post
+		label string
+		err   error
 	)
 	if u.Admin() {
 		label = "Questions you answered"
-		questions, err = s.store.ListQuestionsAnsweredBy(r.Context(), u.ID)
+		posts, err = s.store.ListRootPostsAnsweredBy(r.Context(), u.ID)
 	} else {
 		label = "Your questions"
-		questions, err = s.store.ListQuestionsByAuthor(r.Context(), u.ID)
+		posts, err = s.store.ListRootPostsByAuthor(r.Context(), u.ID)
 	}
 	if err != nil {
 		http.Error(w, "could not load questions", http.StatusInternalServerError)
@@ -275,7 +275,7 @@ func (s *Server) renderProfile(w http.ResponseWriter, r *http.Request, u *store.
 	s.exec(w, "profile", profilePage{
 		page:           p,
 		States:         geo.States,
-		Questions:      questions,
+		Posts:          posts,
 		QuestionsLabel: label,
 		UploadsEnabled: s.cfg.Blob.Enabled(),
 		Error:          errMsg,