Add @linonetwo’s missing change notes (#9409)

* docs

(cherry picked from commit eb5d2c50c0e45712eafda0b0e79bd1816b5f8a5b)
(cherry picked from commit eecfd35336964c756547f9ea622566f8bab02709)

* typo

(cherry picked from commit d9129bcaf3f4face613b3f6ccfe06ce6ed45b2d5)

editions/tw5.com/tiddlers/releasenotes/5.4.0/#8258.tid

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+title: $:/changenotes/5.4.0/#8258
+description: Add ability to serialize WikiText AST nodes back to wikitext strings
+tags: $:/tags/ChangeNote
+change-type: feature
+change-category: developer
+links: https://github.com/TiddlyWiki/TiddlyWiki5/pull/8258
+github-contributors: linonetwo
+
+This PR introduces a new utility `$tw.utils.serializeWikitextParseTree()` that can convert WikiText Abstract Syntax Tree (AST) nodes back into wikitext strings.
+
+There is also a utility `serializeAttribute` for a single attribute node, like an attribute of a widget.
+
+!! Use Cases
+
+* Programmatically manipulating wikitext content by modifying the AST, and use this to write it back
+* Building WYSIWYG editors
+* Creating wikitext formatters and linters
+
+!! Implementation
+
+* New core plugin `tiddlywiki/wikitext-serialize` containing most of the logic
+* Separate serialize handlers for each WikiText rule as `module-type: wikiruleserializer`
+* Test suite with tag `$:/tags/wikitext-serialize-test-spec`
+* It uses each parser's name as rule (`nextMatch.rule.name`), each AST node that needs serialization has a `type` property matching the rule name
+
+!! Example Usage
+
+```javascript
+// Parse a tiddler's wikitext to AST
+var parseTree = $tw.wiki.parseTiddler("MyTiddler").tree;
+
+// Serialize AST back to wikitext string
+var wikitextString = $tw.utils.serializeWikitextParseTree(parseTree).trimEnd();
+```
+
+This feature offers new tools for JS plugin developers. It is not a user-facing change.

editions/tw5.com/tiddlers/releasenotes/5.4.0/#9078.tid

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+title: $:/changenotes/5.4.0/#9078
+description: Web server get-file route now supports HTTP Range headers and streaming
+tags: $:/tags/ChangeNote
+change-type: enhancement
+change-category: nodejs
+links: https://github.com/TiddlyWiki/TiddlyWiki5/pull/9078
+github-contributors: linonetwo
+
+The web server's `get-file` route now supports HTTP Range requests and file streaming, enabling better loading and playback of large media files.
+
+!! Features
+
+* HTTP Range header: Enables partial content delivery with `206 Partial Content` responses, which is used when the user drags the progress bar in video/audio playback
+* Streaming file delivery: Browsers can now properly seek and stream video files from the `/files/` directory. Files are read using Node.js streams for better performance and memory efficiency.
+* Resumable downloads: To save interrupted downloads