Productivity features, UI translations, local email translation

- Snooze (with a Snoozed folder), keyboard shortcuts with a Settings
  section, mail templates (Compose > More > Templates), a Subscriptions
  folder with bulk unsubscribe/delete, and tracker blocking with a
  Privacy toggle (on by default)
- Own dialogs instead of browser popups; emoji picker in compose; compose
  windows survive a visit to Settings
- Sentence completion learned from the user's sent mail (no AI)
- Interface in English and Polish (one file per language, English as the
  fallback), picked from the browser on first run, then kept
- Email translation on the server via LibreTranslate: Translate button
  and "Translate to...", messages in several languages translated part
  by part, names/addresses/emoji/file names/phone numbers kept, an
  animated line while translating
- Antispam "Mark as spam" loads with the message, not when the menu opens

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

backend/tests/test_translation_prep.py

@@ -0,0 +1,128 @@
+"""Getting a message ready for translation (app/translation_prep.py)."""
+
+from __future__ import annotations
+
+from app.translation_prep import (
+    find_names,
+    find_names_in_signature,
+    join_wrapped_lines,
+    keep_symbols,
+    keep_terms,
+    split_pieces,
+    tidy,
+    translate_phrases,
+)
+
+KEPT = '<span translate="no">'
+
+
+def test_wrapped_lines_are_joined_but_paragraphs_kept() -> None:
+    assert join_wrapped_lines("<p>ask you about<br>the schedule.</p>") == (
+        "<p>ask you about the schedule.</p>"
+    )
+    assert join_wrapped_lines("<div>ask you about</div><div>the schedule.</div>") == (
+        "<div>ask you about the schedule.</div>"
+    )
+    text = '<div class="wm-plaintext">ask you about\nthe schedule.\n\nThanks,\nAnna</div>'
+    assert join_wrapped_lines(text) == (
+        '<div class="wm-plaintext">ask you about the schedule.\n\nThanks,\nAnna</div>'
+    )
+    # A new sentence, or a capital after the break: left alone.
+    for html in ("<p>Done.<br>then more</p>", "<p>Hi Lukas,<br>Natalia</p>"):
+        assert join_wrapped_lines(html) == html
+
+
+def test_sign_offs_come_from_the_phrase_table() -> None:
+    assert translate_phrases("<p>Best,<br>Natalia</p>", "en", "pl") == (
+        f"<p>{KEPT}Pozdrawiam,</span><br>Natalia</p>"
+    )
+    assert translate_phrases("<div>Mit freundlichen Grüßen</div>", "de", "en") == (
+        f"<div>{KEPT}Kind regards</span></div>"
+    )
+    assert "Pozdrawiam" not in translate_phrases("<p>Best results so far</p>", "en", "pl")
+    assert translate_phrases("<p>Best,</p>", "fr", "pl") == "<p>Best,</p>"  # no table
+
+
+def test_names_mid_sentence_but_not_headlines_or_german() -> None:
+    html = "<p>I came across Imaginary Pixels and Trusted Partner Network, in Spain.</p>"
+    assert find_names(html, "en") == {"Imaginary Pixels", "Trusted Partner Network"}
+    assert find_names("<p>Why Matchmoving Matters, Editing Digger And More</p>", "en") == set()
+    assert find_names("<p>Wir haben das Neue Angebot gesehen.</p>", "de") == set()
+    # Not across a sentence's end.
+    assert find_names("<p>working mostly in NukeX. My work includes paint.</p>", "en") == set()
+    assert find_names_in_signature("Imaginary Pixels – visual effects studio") == [
+        "Imaginary Pixels"
+    ]
+
+
+def test_kept_terms_and_spacing() -> None:
+    out = keep_terms(
+        "<p>Hi Natalia Raz, see Imaginary Pixels.</p>", ["Natalia Raz", "Imaginary Pixels"]
+    )
+    assert out == f"<p>Hi {KEPT}Natalia Raz</span>, see {KEPT}Imaginary Pixels</span>.</p>"
+    assert keep_terms("<style>.Natalia{}</style>", ["Natalia"]) == "<style>.Natalia{}</style>"
+    assert tidy(f"nad {KEPT}Bruton</span>i dalej") == f"nad {KEPT}Bruton</span> i dalej"
+    assert tidy("<span>a</span>b") == "<span>a</span>b"  # the sender's own spans
+
+
+def test_emoji_kept() -> None:
+    html = (
+        '<p>nice to e-meet you <span style="font-family:Segoe UI Emoji">\n😊</span> &nbsp;</p>'
+        "<p>Great 👍🏽 work ❤️</p>"
+    )
+    out = keep_symbols(html)
+    assert f"{KEPT}😊</span>" in out
+    assert f"{KEPT}👍🏽</span>" in out
+    assert f"{KEPT}❤️</span>" in out
+    assert "nice to e-meet you" in out  # the words still go to translation
+
+
+def test_file_names_kept() -> None:
+    html = (
+        "<li>A_0023C017_260521_130157_p1CAC.mov</li>"
+        "<p>See final_v2 and plate-03.exr, e.g. the U.S cut.</p>"
+    )
+    out = keep_symbols(html)
+    assert f"{KEPT}A_0023C017_260521_130157_p1CAC.mov</span>" in out
+    assert f"{KEPT}final_v2</span>" in out
+    assert f"{KEPT}plate-03.exr</span>" in out
+    assert "e.g. the U.S cut" in out  # no file names there
+
+
+def test_symbols_not_marked_twice_or_in_attributes() -> None:
+    html = (
+        f'<a href="https://x.io/a_b.mov">{KEPT}https://x.io/a_b.mov</span></a>'
+        "<style>.a_b{}</style>"
+    )
+    assert keep_symbols(html) == html
+
+
+def test_text_without_letters_is_kept() -> None:
+    # A byte-order mark alone between tags came back as "Uzasadnienie".
+    out = keep_symbols(
+        '<div dir="ltr">\ufeff<div>Dear Lukas,</div><div> &nbsp; </div><p> – </p></div>'
+    )
+    assert f"{KEPT}\ufeff</span>" in out
+    assert "<div> &nbsp; </div>" in out  # only spaces: nothing to keep
+    assert f"<p> {KEPT}–</span> </p>" in out
+    assert "<div>Dear Lukas,</div>" in out
+
+
+def test_handles_and_phone_numbers_kept() -> None:
+    out = keep_symbols(
+        "<p>WeChat: Jacquelineeeee_ WhatsApp: +48 780 549 877, for 1300 - 2500 Euro</p>"
+    )
+    assert f"{KEPT}Jacquelineeeee_</span>" in out
+    assert f"{KEPT}+48 780 549 877</span>" in out
+    assert "1300 - 2500 Euro" in out  # plain numbers stay in their sentence
+
+
+def test_paragraphs_split_at_block_tags() -> None:
+    html = (
+        f"<style>p{{}}</style><div>Dear <b>Anna</b>,<br>hello {KEPT}x.mov</span> there</div>"
+        "<p> &nbsp; </p><li>Item</li>"
+    )
+    pieces, paragraphs = split_pieces(html)
+    assert [p.text for p in paragraphs] == ["Dear Anna,", "hello x.mov there", "Item"]
+    # The kept file name counts for the language but is not translated.
+    assert [pieces[i] for i in paragraphs[1].pieces] == ["hello ", " there"]