refactor: preserve URL search params during navigation

Introduce `useNavigateWithParams` to ensure that existing URL search
parameters are maintained when navigating between pages. This is
applied to the Article component, FileTree, and journal links to
prevent losing state (like session or player info) during client-side
navigation.

Also intercepts markdown anchor links in the Article component to use
client-side navigation.

src/components/journal/types/link.tsx

@@ -6,7 +6,7 @@
  */
 
 import { Component } from "solid-js";
-import { useNavigate } from "@solidjs/router";
+import { useNavigateWithParams } from "../../useNavigateWithParams";
 import { z } from "zod";
 import { registerMessageType } from "../registry";
 import { journalSetState } from "../../stores/journalStream";
@@ -22,7 +22,7 @@ export type LinkPayload = z.infer<typeof schema>;
 
 function fileNameFromPath(path: string): string {
   const parts = path.split("/").filter(Boolean);
-  return parts[parts.length - 1] || path;
+  return decodeURIComponent(parts[parts.length - 1] || path);
 }
 
 /** Encode a path, preserving / separators but encoding each segment */
@@ -42,7 +42,7 @@ function slugToTitle(slug: string): string {
 }
 
 const RevealLink: Component<LinkPayload> = (p) => {
-  const navigate = useNavigate();
+  const navigate = useNavigateWithParams();
 
   const target = () => {
     let t = encodePath(p.path);