docs: write README and AGENT.md

Assisted-by: Delta:zai-glm-5.3

AGENT.md

@@ -0,0 +1,5 @@
+# Agent Rules for Yggdrasil Migration
+
+*   **Commit Policy**: Small conventional commits. One logical change per commit. Must be committed only once that step is verified and working. Append `Assisted-by: Delta:gemini-3.1-pro` to the footer.
+*   **Toolchain**: Pinned versions of `calepin` (0.0.61) and `typst` (0.15.1) are downloaded locally into `tools/`. Global installs must not be used by the build process.
+*   **Verification**: Ensure all builds pass locally (`just clean`, `just tools`, `just build`) before committing changes to track files correctly. Do not alter legacy documentation in `legacy_docs/`.

README.md

@@ -1,33 +1,20 @@
-<header>
-  <h1>Yggdrasil</h1>
-</header>
-Yggdrasil is a collections of notes around IT, OT and other geeks stuff
-<br>
-<br>
-<br>
+# Yggdrasil
 
-# [Bachelor in embedded system](/infotro/)
-Here notes I take during my bachelor in embedded systems
+A knowledge base migrated to [Calepin](https://vincentarelbundock.github.io/calepin/), a Typst-based static site generator.
 
-Mainly some topics:
-- [PTR - Programmation Temps Réel](/infotro/PTR/)
-- [SDi - Système Distribué](/infotro/SDi/)
-- [Eln - Électronique](/infotro/Eln/)
-- [SEm - Systèmes Embarqué](/infotro/SEm/)
+## Quick Start
 
-# [Master of science in engineering in embedded system](/MSE/)
-Here note I take during my Master of science un engineering with embedded system as orientation
+1.  **Dependencies**: You need the `just` command runner.
+2.  **Bootstrap Toolchain**: Run `just tools`. This downloads pinned versions of `calepin` and `typst` into the `tools/` directory. No global installation is required.
+3.  **Build**: Run `just build` to generate the static site in the `public/` directory.
+4.  **Preview**: Run `just preview` or `just watch` to view the site locally.
 
-Mainly some topics:
-- [SRE - Software Reverse Engineering](/MSE/SRE/)
+## Adding Content
 
-# [Embedded Systems](/Embed/)
-Here some note specific about some Embedded System
-- [STM32](/Embed/STM32/)
-- [nRF](/Embed/nRF/)
+*   Source files are located in `site/`.
+*   To add a page, create a `.typ` file and link it in the `site/calepin.toml` configuration under `[sidebar]` or `[pages]`.
+*   Categories are structured as subdirectories (e.g., `site/thermo/`) with their own `index.typ`.
 
-# [Working environment at HES-SO](/HES-SO/)
-Here some note about the working environment at HES-SO
+## Deployment
 
-- [OneDrive - Linux](/HES-SO/OneDrive.md)
-- [Teams - Linux](/HES-SO/Teams.md)
+The site is built as a set of static files in the `public/` folder. A Gitea Actions workflow `.gitea/workflows/build.yml` runs on push to build and upload these files as an artifact. They can be deployed to any static host.