fix(web): decode percent-encoded slugs in the knowledge content route

chi.URLParam returns the raw, still-encoded path segment — unlike the
OpenAPI-generated routes, which decode via
runtime.BindStyledParameterWithOptions before the handler sees them. Slugs
like "document:containers/101-jellyfin" (encoded by the frontend's
encodeURIComponent) were arriving undecoded and matching no row. Found via
a standalone chi repro, not by patching the live deploy checkout.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

internal/httpapi/knowledge.go

@@ -5,6 +5,7 @@ import (
 	"encoding/json"
 	"log/slog"
 	"net/http"
+	"net/url"
 	"strconv"
 
 	"github.com/dtoro/oikos/internal/httpapi/gen"
@@ -116,12 +117,21 @@ func (s *Server) serveRecentKnowledge(w http.ResponseWriter, req *http.Request)
 // panel needs the entity's own full content when it IS a knowledge entity.
 func (s *Server) serveKnowledgeContent(w http.ResponseWriter, req *http.Request) {
 	ctx := req.Context()
-	idOrSlug := chi.URLParam(req, "id")
+	// chi.URLParam returns the raw, still-percent-encoded segment (unlike
+	// the OpenAPI-generated routes, which decode via
+	// runtime.BindStyledParameterWithOptions before reaching the handler) —
+	// slugs like "document:containers/101-jellyfin" arrive as
+	// "document%3Acontainers%2F101-jellyfin" and must be unescaped here.
+	idOrSlug, err := url.PathUnescape(chi.URLParam(req, "id"))
+	if err != nil {
+		writeProblem(w, req, http.StatusBadRequest, "invalid id", err.Error())
+		return
+	}
 
 	var title, content, source string
 	var tags []string
 	var updatedAt string
-	err := s.pool.QueryRow(ctx, `
+	err = s.pool.QueryRow(ctx, `
 		SELECT ke.title, ke.content, COALESCE(ke.source,''), ke.tags, ke.updated_at::text
 		FROM knowledge_entities ke
 		JOIN entities e ON e.id = ke.entity_id