feat(webui): migrate /proposals to consolidated dark theme with shared nav (#1632)

Move proposals list and detail templates from layout-based (sidebar) to
standalone pages with shared nav partial and Tailwind dark theme
utilities. Update handlers to use Execute instead of ExecuteTemplate
for standalone template rendering.

Closes #1628

Author: nextlevelshit

internal/webui/embed.go

@@ -48,8 +48,6 @@ var pageTemplates = []string{
 	"templates/webhook_detail.html",
 	"templates/admin.html",
 	"templates/onboard/index.html",
-	"templates/proposals/list.html",
-	"templates/proposals/detail.html",
 }
 
 // standalonePageTemplates is the list of templates that do NOT extend
@@ -62,6 +60,8 @@ var pageTemplates = []string{
 var standalonePageTemplates = []string{
 	"templates/work/board.html",
 	"templates/work/detail.html",
+	"templates/proposals/list.html",
+	"templates/proposals/detail.html",
 }
 
 // parseTemplates parses all embedded HTML templates using a clone-per-page

internal/webui/handlers_proposals.go

@@ -115,7 +115,7 @@ func (s *Server) handleProposalsPage(w http.ResponseWriter, r *http.Request) {
 		http.Error(w, "template missing: proposals/list.html", http.StatusInternalServerError)
 		return
 	}
-	if err := tmpl.ExecuteTemplate(w, "templates/layout.html", view); err != nil {
+	if err := tmpl.Execute(w, view); err != nil {
 		http.Error(w, "template error: "+err.Error(), http.StatusInternalServerError)
 	}
 }
@@ -166,7 +166,7 @@ func (s *Server) handleProposalDetailPage(w http.ResponseWriter, r *http.Request
 		http.Error(w, "template missing: proposals/detail.html", http.StatusInternalServerError)
 		return
 	}
-	if err := tmpl.ExecuteTemplate(w, "templates/layout.html", view); err != nil {
+	if err := tmpl.Execute(w, view); err != nil {
 		http.Error(w, "template error: "+err.Error(), http.StatusInternalServerError)
 	}
 }