Add German translation

[daPhipz]

I translated the application in German.
There are some things that I noticed and may need additional clarification via a Translator comment or by specifying a singular/plural form:

#. TRANSLATORS: {num} is the total number of seasons
#: src/pages/details_page.py:161
#, python-brace-format
msgid "{num} Seasons"
msgstr "{num} Staffeln"

#. TRANSLATORS: {num} is the total number of episodes
#: src/pages/details_page.py:166 src/pages/details_page.py:195
#, python-brace-format
msgid "{num} Episodes"
msgstr "{num} Episoden"

#. TRANSLATORS: {number} is the number of titles
#: src/preferences.py:315 src/preferences.py:316
#, python-brace-format
msgid "{number} Titles"
msgstr "{number} Titel"

These 3 strings need a singular form.

#: src/ui/preferences.blp:23
msgctxt "preferences"
msgid "Complete Setup"
msgstr ""

Is this a button label (aka "Click here to complete the setup") or does it mean "Whole setup" vs "Partial setup"?

#: src/ui/dialogs/add_manual.blp:53 src/views/main_view.py:54
#: src/widgets/search_result_row.py:78
msgid "TV Series"
msgstr "Serie"

Is this string singular or plural? It doesn't matter in English, but in other languages, there are different words (in German "Serie" and "Serien")

[aleiepure]

Even though I speak 4 languages, while coding my brain is wired up to think as if English is the only language on Earth.
I've updated the translation template with your suggestions. Hopefully, it's clearer now (if not ask away). Please review your translation and make the necessary corrections so that I can merge it.

Next time, please use weblate for future translations and updates.

[daPhipz]

I updated the translation. Thanks for your time incorporating the changes!