docs: restructure docs into diataxis (#121)

docs/tutorials/first-run.md

@@ -0,0 +1,32 @@
+# First run
+
+You’ll run Takopi in a repo, send a task from Telegram, and learn the basic controls.
+
+## 1) Start Takopi in a repo
+
+```sh
+cd ~/dev/your-repo
+takopi
+```
+
+## 2) Send a message to your bot
+
+Takopi streams progress in chat and posts a final message when the engine finishes.
+
+If you want to override the default engine for a single message, prefix the first line:
+
+```
+/codex explain this code
+/claude refactor this module
+```
+
+## 3) Continue or cancel
+
+- Continue the same thread by **replying** to any bot message that contains a resume line in the footer.
+- Cancel an in-flight run by clicking the cancel button or replying to the progress message with `/cancel`.
+
+## Next
+
+- [Projects](../how-to/projects.md) and [Worktrees](../how-to/worktrees.md)
+- [Commands & directives](../reference/commands-and-directives.md)
+