feat: content import system - Markdown parser, importer, 7 decks + 3 tutorials + 5 cheatsheets

edu/content/cheatsheets/commands-cheatsheet.md

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+# Omnis Commands Cheat Sheet
+
+## Die 10 wichtigsten Befehle
+
+| # | Befehl | Was es tut | JS-Aequivalent |
+|---|--------|-----------|----------------|
+| 1 | `Calculate lX as expr` | Berechnung + Zuweisung | `let x = expr` |
+| 2 | `Do obj.$method()` | Methodenaufruf | `obj.method()` |
+| 3 | `If ... Else ... End If` | Bedingung | `if ... else ...` |
+| 4 | `For i from a to b step c` | Zaehlschleife | `for (let i=a; i<=b; i+=c)` |
+| 5 | `For each line in list` | Listen-Iteration | `for (const item of arr)` |
+| 6 | `While ... End While` | Bedingungsschleife | `while (...)` |
+| 7 | `Quit method lVal` | Methode beenden + Return | `return val` |
+| 8 | `OK message {text}` | Nachricht anzeigen | `alert(text)` |
+| 9 | `Switch ... Case ... End Switch` | Fallunterscheidung | `switch ... case` |
+| 10 | `Do inherited` | Super-Methode rufen | `super.method()` |
+
+## Variablen & Berechnung
+```omnis
+Calculate lName as "Harry"               String zuweisen
+Calculate lSum as lA + lB                Berechnen
+Calculate lText as con("Hallo ", lName)  String verketten
+Calculate lUpper as upp(lName)           Grossbuchstaben
+Calculate lLen as len(lName)             String-Laenge
+Calculate lSub as mid(lName, 2, 3)       Substring
+Calculate lPos as pos("r", lName)        Zeichen finden
+```
+
+## Kontrollfluss
+```omnis
+If lAge >= 18                 If lStatus = 'A' | lStatus = 'B'
+  # erwachsen                   # A oder B
+Else If lAge >= 14            End If
+  # jugendlich
+Else                          Switch lStatus
+  # kind                        Case 'A'
+End If                            # aktiv
+                                Case 'I'
+While lX < 100                    # inaktiv
+  Calculate lX as lX + 1       Default
+End While                         # sonstiges
+                              End Switch
+For lI from 1 to 10 step 1
+  # lI = 1, 2, 3, ...10
+End For
+```
+
+## Dialoge
+```omnis
+OK message {Fertig!}                          Info-Dialog
+Yes/No message {Loeschen?}                    Ja/Nein Dialog
+  If flag true ... End If                     Ergebnis pruefen
+Prompt for input {Name?} lName                Eingabe-Dialog
+No/Yes message {Abbrechen?}                   Nein/Ja (Default=Nein)
+```
+
+## Debugging
+```omnis
+Breakpoint                    Debugger oeffnen (= debugger; in JS)
+OK message {Debug: [lVar]}    Quick-Debug mit Message
+Trace log {[lVar]}            In Trace-Log schreiben
+```
+
+## SQL-Befehle (ueber Session/Statement)
+```omnis
+Do lSess.$logon(host, user, pw, 'sess') Returns #F   Verbinden
+Do lStmt.$prepare('SELECT...WHERE id=:1') Returns #F  Vorbereiten
+Do lStmt.$execute(lID) Returns #F                      Ausfuehren
+Do lStmt.$fetch(lList, kFetchAll) Returns #F           Ergebnis holen
+Do lStmt.$execdirect('INSERT...') Returns #F           Direkt ausfuehren
+```
+
+## Merkhilfe: Die Befehls-Familien
+```
+DATEN:    Calculate, Do, Set current list
+FLUSS:    If/Else/End If, For/End For, While/End While, Switch/Case/End Switch
+METHODE:  Quit method, Do inherited, Quit all methods
+DIALOG:   OK message, Yes/No message, Prompt for input
+FENSTER:  Open window, Close window, Redraw, Enter data
+SQL:      $logon, $prepare, $execute, $fetch, $execdirect
+```