Break A and E technical into subdecks

CLAUDE.md

@@ -44,8 +44,8 @@ BNetzA ZIP ──[Stage 1: amateurfunk_fetch.py]──► data/<slug>/
 
 data/ ──[Stage 2: amateurfunk_anki.py]──► anki/
                                             ├── amateurfunk-technische-kenntnisse-n.apkg
-                                            ├── amateurfunk-technische-kenntnisse-e.apkg
-                                            ├── amateurfunk-technische-kenntnisse-a.apkg
+                                            ├── amateurfunk-technische-kenntnisse-e.apkg  (one file, 11 topic sub-decks)
+                                            ├── amateurfunk-technische-kenntnisse-a.apkg  (one file, 11 topic sub-decks)
                                             ├── amateurfunk-betriebliche-kenntnisse.apkg
                                             └── amateurfunk-kenntnisse-von-vorschriften.apkg
 
@@ -76,10 +76,16 @@ technical.json ──[Stage 2c: amateurfunk_technical.py]──► anki/
    `manifest-latest.json` to a per-edition directory).
 2. Split the catalog into five categories. Betriebliche and
    Vorschriften get one deck each (shared across every candidate).
-   Technische is additionally fanned out per license class into three
-   decks (N / E / A) using a strict equality split on the question's
-   `class` field. The `klasse-N|E|A` tag is still emitted on every
-   note for inside-Anki filtering.
+   Technische is additionally fanned out per license class using a
+   strict equality split on the question's `class` field: one `.apkg`
+   each for N, E, and A. The E (463) and A (716) packages — the large
+   pools — are each built as a deck *tree*: one sub-deck per
+   first-level catalog topic (the 11 subsections) under an anchoring
+   `Technische Kenntnisse::E` / `::A` parent, so each imports as a
+   single file but studies topic by topic. N stays a single flat deck.
+   The set of split classes is `TOPIC_SPLIT_CLASSES`. The
+   `klasse-N|E|A` tag is still emitted on every note for inside-Anki
+   filtering.
 3. Render every question as an Anki note: shuffled A/B/C/D choices on
    the front, the displayed position of the correct answer on the
    back. Inline `$...$` LaTeX is converted to MathJax `\(...\)`