attachments preview overlay, docx/xlsx/odf rendering, composer drag-drop & undo-send UX

Frontend:
- Full-screen attachment preview overlay (AttachmentPreview) for image/pdf/txt
  plus office docs: .docx via docx-preview (rendered live into the sandboxed
  iframe so header/footer VML images survive), .xlsx via xlsx-preview, and
  .odt/.ods/.odp/.odg via a JSZip+DOMParser ODF walker (officeConvert).
- Type-aware attachment icons (green spreadsheet, blue document, red PDF,
  image/archive); new document/image/spreadsheet/print SVGs.
- Composer: drag-drop attachments (body drop inserts images inline, else
  attaches); inserted images are selectable/resizable/deletable (RichTextEditor).
- Undo-send: "Sending…" banner with live "N seconds to Undo" countdown.
- Search result list: pin/archive/delete update correctly; grey-out only for
  search hits; scoped "Search in Trash/Spam".

Backend:
- Search: prefix (search-as-you-type) matching, email-address search, and
  address-first result ordering; Trash/Junk excluded with scoped folder search.
- Attachments: RFC 6266 Content-Disposition for non-ASCII filenames; one-time
  inline image loading.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01Rcj3TpydMTzTSmU7kunzf8

backend/tests/api/test_api.py

@@ -234,6 +234,42 @@ async def test_attachments_list_and_zip(api: ApiCtx) -> None:
     assert archive.read("notes.txt") == b"hello attachment"
 
 
+async def test_attachment_download_non_ascii_filename(api: ApiCtx) -> None:
+    # A Polish filename (ł, ń) is not Latin-1, which would crash the response with
+    # a 500 if put raw in Content-Disposition. It must serve 200 with RFC 6266.
+    from app.indexer import blobstore
+    from app.models import Attachment
+
+    assert api.session is not None
+    mid = api.message_ids[-1]
+    payload = b"PK\x03\x04 zip-ish bytes"
+    sha = blobstore.store(api.user_id, payload)
+    name = "oferta - składowe ceny.ods"
+    api.session.add(
+        Attachment(
+            message_id=mid,
+            user_id=api.user_id,
+            filename=name,
+            mime_type="application/vnd.oasis.opendocument.spreadsheet",
+            size_bytes=len(payload),
+            content_id=None,
+            blob_sha256=sha,
+        )
+    )
+    await api.session.commit()
+
+    aid = next(
+        a["id"] for a in (await api.client.get(f"/api/messages/{mid}/attachments")).json()
+        if a["filename"] == name
+    )
+    resp = await api.client.get(f"/api/messages/{mid}/attachments/{aid}")
+    assert resp.status_code == 200  # not 500
+    assert resp.content == payload
+    cd = resp.headers["content-disposition"]
+    assert "filename*=UTF-8''" in cd  # UTF-8 encoded name for modern clients
+    assert "sk%C5%82adowe" in cd  # ł percent-encoded
+
+
 async def test_quota_reports_usage_and_default(api: ApiCtx) -> None:
     resp = await api.client.get("/api/settings/quota")
     assert resp.status_code == 200

backend/tests/search/test_search_api.py

@@ -86,6 +86,8 @@ async def _ingest(
     body: str,
     flags: frozenset[str] = frozenset(),
     attach: bool = False,
+    mailbox_id: uuid.UUID | None = None,
+    special: str = "inbox",
 ) -> None:
     ctx.uid += 1
     m = EmailMessage()
@@ -101,8 +103,8 @@ async def _ingest(
         ctx.session,
         user_id=ctx.user_id,
         account_id=ctx.account_id,
-        mailbox_id=ctx.mailbox_id,
-        mailbox_special_use="inbox",
+        mailbox_id=mailbox_id or ctx.mailbox_id,
+        mailbox_special_use=special,
         remote=RemoteMessage(
             uid=ctx.uid, raw=m.as_bytes(), flags=flags, internal_date=datetime.now(UTC)
         ),
@@ -145,6 +147,25 @@ async def seeded(ctx: Ctx) -> Ctx:
     return ctx
 
 
+async def test_search_excludes_trash_by_default(ctx: Ctx) -> None:
+    # Deleting a message from search results (it moves to Trash) removes it from the
+    # results — search excludes Trash/Junk unless in:trash/in:junk asks for them.
+    from app.models import Mailbox
+
+    await _ingest(ctx, frm="Bob <bob@corp.com>", subject="quarterly zephyr", body="hi")
+    trash = Mailbox(
+        account_id=ctx.account_id, user_id=ctx.user_id, path="Trash", special_use="trash"
+    )
+    ctx.session.add(trash)
+    await ctx.session.flush()
+    await _ingest(
+        ctx, frm="X <x@corp.com>", subject="zephyr in trash", body="bye",
+        mailbox_id=trash.id, special="trash",
+    )
+    assert await _search(ctx, "zephyr") == 1  # inbox only; the trashed one is hidden
+    assert await _search(ctx, "in:trash zephyr") == 1  # explicit -> searches Trash
+
+
 async def test_free_text(seeded: Ctx) -> None:
     assert await _search(seeded, "revenue") == 1
     assert await _search(seeded, "lunch") == 1