chore: add the BuildKit entry and fold the install tool into the size entry

The install tool now leaves every image rather than only the slim one, since it
is mounted for the install step instead of being installed and removed, so the
size entry names it among what the image no longer carries and the slim clause
keeps only the source maps.

Changed records what building the image yourself now takes: the BuildKit
builder, which the syntax line alone did not require before, and reach to the
registry that tool is fetched from.

CHANGELOG.md

@@ -15,7 +15,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - 🏷️ **Custom file metadata.** Metadata attached to an uploaded file now travels with the pieces that file is split into and arrives with the retrieved sources, the oversized and internal fields left out. [#29499](https://github.com/open-webui/open-webui/pull/29499), [#29486](https://github.com/open-webui/open-webui/issues/29486), [Commit](https://github.com/open-webui/open-webui/commit/894655f66b9563890e63c76090ddecc90a311eb2), [#29502](https://github.com/open-webui/open-webui/pull/29502)
 - 🗑️ **Quick delete for notes and automations.** Holding Shift over a note in the list or grid, or over a row on the automations page, turns its trailing controls into a delete button, removing the entry in one click rather than the three the menu and its confirmation ask for. [#29635](https://github.com/open-webui/open-webui/pull/29635), [#29633](https://github.com/open-webui/open-webui/issues/29633), [#29640](https://github.com/open-webui/open-webui/pull/29640), [#29637](https://github.com/open-webui/open-webui/issues/29637)
 - ⚡ **Searching without holding up the server.** Searching the text of chats and knowledge now runs beside the rest of the server rather than in front of it, so a long search no longer keeps other requests waiting. [#29621](https://github.com/open-webui/open-webui/pull/29621)
-- 📦 **A smaller container image.** The image no longer carries a second copy of Python, a set of fonts nothing ever loaded, or packages nothing imports, taking around 250 MB off what has to be pulled, and the slim image also leaves behind the tool that installed its packages and the source maps built beside the interface. [#29731](https://github.com/open-webui/open-webui/pull/29731), [#29723](https://github.com/open-webui/open-webui/pull/29723), [#29725](https://github.com/open-webui/open-webui/pull/29725), [#29726](https://github.com/open-webui/open-webui/pull/29726), [Commit](https://github.com/open-webui/open-webui/commit/91f8775b28b52c9ae7f2ab990cf2490bda8055d6)
+- 📦 **A smaller container image.** The image no longer carries a second copy of Python, a set of fonts nothing ever loaded, packages nothing imports, or the tool that installed them, taking about 300 MB off the image, and the slim build also leaves behind the source maps built beside the interface. [#29731](https://github.com/open-webui/open-webui/pull/29731), [#29723](https://github.com/open-webui/open-webui/pull/29723), [#29725](https://github.com/open-webui/open-webui/pull/29725), [#29726](https://github.com/open-webui/open-webui/pull/29726), [#29728](https://github.com/open-webui/open-webui/pull/29728), [Commit](https://github.com/open-webui/open-webui/commit/91f8775b28b52c9ae7f2ab990cf2490bda8055d6)
 - 🔄 **General improvements.** Various improvements were implemented across the application to enhance performance, stability, and security.
 - 🌐 **Translation updates.** Translations for Traditional Chinese, Korean, Finnish, Russian, Ukrainian, German, Spanish, and Portuguese (Brazil) were enhanced and expanded.
 
@@ -50,6 +50,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - 🔗 **Default suggestions answer with an object.** Saving the default prompt suggestions now answers with the suggestions and their per-language wording together rather than the bare list it returned before, which anything calling it directly will need to read. [Commit](https://github.com/open-webui/open-webui/commit/7b6562e3358956ec71eed05352538a646d047734)
 - 🖼️ **Default picture without access.** A model picture now falls back to the standard logo wherever the viewer holds no grant on that model, such as a model reply shown to the other members of a channel, or the admin analytics and evaluation pages with the access bypass switched off. [#29700](https://github.com/open-webui/open-webui/pull/29700)
 - 🪶 **Slim leaves the heavy work outside.** An instance built slim starts and holds a conversation with nothing extra configured, but the features that leaned on the local models it no longer carries, knowledge search, document extraction past plain text and speech, each ask for a service of their own the first time they are used, and it can no longer be built together with the graphics card or Ollama options. [Commit](https://github.com/open-webui/open-webui/commit/cb942bb94c8dc7941336088fb3392e2398ff56c1)
+- 🧱 **Building the image needs BuildKit.** Building Open WebUI yourself now takes the BuildKit builder and reach to the registry the install tool is fetched from, next to the package index it already needed. [#29728](https://github.com/open-webui/open-webui/pull/29728)
 - 🧾 **Tools declare what they import.** A tool or function importing a package that was only ever present by accident, among them nltk, pymongo and the Google Drive client, now has to name it in its requirements, or have it installed into the image where the instance cannot reach the package index. [#29725](https://github.com/open-webui/open-webui/pull/29725), [#29726](https://github.com/open-webui/open-webui/pull/29726)
 
 ## [0.11.3] - 2026-08-31