Polish /report-bug's visual design and refine bug report semantics

Design pass on the bug report page, staying inside the site's existing
design system (tokens, IBM Plex Sans, card/badge/pill components, stroke
icon set) rather than introducing a new one:
- A slim top bar (brand mark + back-to-home pill button + language switcher)
  replaces the bare floating heading, so the page reads as part of the
  product instead of an orphaned form.
- The "write in English" notice moves inside the form card, right above the
  field it applies to, and switches from the amber "needs attention" tone to
  an accent-tinted info tone, so it doesn't visually collide with the
  bug-status badges' own use of amber for "not read yet".
- "Your reports" is promoted to a proper labeled section with a cleaner row
  layout (truncated description with a title tooltip, compact date).
- A character counter on the description field.
- The back-to-home control is now a bordered pill with an arrow icon instead
  of a bare text link with a hardcoded "←", which also meant dropping that
  hardcoded arrow from all 7 translations.

Also, two content refinements based on feedback:
- Max description length dropped from 5000 to 2000 characters, enforced on
  both the textarea and the API's Pydantic validator.
- The "read" status is relabeled from a passive "read"/"letta" to an active
  "acknowledged"/"presa in carico" (and each other language's own equivalent
  helpdesk term) — it communicates a team is on it, not just that someone
  glanced at it. Only the label changed; the underlying "read" status value
  in the API/DB is untouched.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

app/api/routes/bug_reports.py

@@ -12,7 +12,7 @@ router = APIRouter(prefix="/bug-reports", tags=["bug-reports"])
 
 
 class BugReportCreate(BaseModel):
-    description: str = Field(min_length=1, max_length=5000)
+    description: str = Field(min_length=1, max_length=2000)
     contact: str | None = Field(default=None, max_length=256)
 
     @field_validator("description")