fix(i18n): every refusal the API answers is structured and said in the reader's language

~150 HTTPExceptions carried a hand-written English sentence as their detail,
shown verbatim under the Hungarian UI — in the blocking error dialog and on
every inline surface that printed HttpError.detail (sign-in, setup wizard,
change password, the passphrase gate, live search). Four also quoted an
upstream exception's text back to the user.

- app/refusal.py: `refused(status, reason, **params)` → {code: "refused",
  reason, …params}; localizeDetail translates errors.refused.<reason> with the
  params interpolated. "Unknown X" 404s use the existing not_found(what).
- sysconfig.set_value raises InvalidSetting (reason + bounds) instead of an
  English ValueError; the three writers answer it through setting_refused.
- The Plex connection/write/image failures log what the upstream said and
  answer a reason; the search scraper's failure is logged and answered as
  youtube/unavailable (it crashed refusal_reason before).
- HttpError.detail now only ever holds a translated reason: a string detail
  (only the framework's own can remain) is left out, so reading .detail is
  safe everywhere — including destructured, the hole the raw-detail source
  scan could not see. That scan and its five-file exception list are gone.
- Enforced: test_http_details.py fails on any HTTPException with a sentence
  for a detail; the contract test requires every refused reason and every
  not_found "what" in both languages, and no key for one that is gone.
- local/jsx-comment-text: a // inside JSX children renders as text; the rule
  is ten lines in eslint.config.js rather than eslint-plugin-react's ~1800
  lockfile lines.

backend/app/routes/plex/collections.py

@@ -9,6 +9,7 @@ from pydantic import BaseModel
 from sqlalchemy import func, select
 from sqlalchemy.orm import Session
 
+from app import logs
 from app.auth import admin_user, current_user
 from app.db import get_db
 from app.models import (
@@ -26,6 +27,10 @@ from app.plex.client import PlexClient, PlexError, PlexNotConfigured
 from app.plex.lookups import by_rating_key
 from app.plex.query import content_libs, runtime_by_key, top_art_keys
 from app.utils import like_escape
+from app.refusal import refused
+from app.routes._common import not_found
+
+log = logs.get_logger(__name__)
 
 # The most-restrictive → least ordering used to pick a collection's effective content rating from its
 # members (Plex shows one cert on the collection; we don't store it, so derive it).
@@ -234,7 +239,7 @@ def collection_detail(
     endpoints below."""
     col = by_rating_key(db, PlexCollection, rating_key)
     if col is None:
-        raise HTTPException(status_code=404, detail="Unknown collection")
+        raise not_found("collection")
     movies = (
         db.execute(
             select(PlexItem)
@@ -325,9 +330,9 @@ def collection_detail(
 def _editable_collection_or_403(db: Session, rating_key: str) -> PlexCollection:
     col = by_rating_key(db, PlexCollection, rating_key)
     if col is None:
-        raise HTTPException(status_code=404, detail="Unknown collection")
+        raise not_found("collection")
     if not _collection_editable(col):
-        raise HTTPException(status_code=403, detail="This collection is read-only")
+        raise refused(403, "collection_read_only")
     return col
 
 
@@ -362,14 +367,13 @@ def _write_or_pending_error(wrote: bool, e: Exception) -> HTTPException:
     Both use 422, NOT a 5xx: the frontend treats 502/503/504 as "gateway unreachable" and raises a
     sticky offline banner (see api/core.ts RETRIABLE_GATEWAY). A 422 surfaces the detail as an ordinary
     action-error toast, which is what both of these are — the app answered, it didn't go unreachable."""
-    if wrote:
-        detail = (
-            "Collection updated in Plex, but refreshing the local copy failed; "
-            f"it will reconcile on the next sync ({e})"
-        )
-    else:
-        detail = f"Plex write failed: {e}"
-    return HTTPException(status_code=422, detail=detail)
+    log.warning(
+        "a Plex collection write did not settle",
+        extra=logs.event(
+            "plex.collections.write_failed", wrote=wrote, reason=type(e).__name__, error=str(e)
+        ),
+    )
+    return refused(422, "collection_pending_sync") if wrote else refused(422, "plex_write_failed")
 
 
 class CreateCollectionIn(BaseModel):
@@ -389,7 +393,7 @@ def create_collection(
     title = body.title.strip()
     seed = body.item_rating_key
     if not title or not seed:
-        raise HTTPException(status_code=400, detail="title and item_rating_key are required")
+        raise refused(400, "collection_fields_required")
     if library:
         lib = (
             db.execute(select(PlexLibrary).where(PlexLibrary.plex_key == library)).scalars().first()
@@ -399,7 +403,7 @@ def create_collection(
         seed_item = by_rating_key(db, PlexItem, seed) or by_rating_key(db, PlexShow, seed)
         lib = db.get(PlexLibrary, seed_item.library_id) if seed_item else None
     if lib is None:
-        raise HTTPException(status_code=404, detail="Unknown library")
+        raise not_found("library")
     _reject_duplicate_name(db, lib.id, title)
     wrote = False
     try:
@@ -473,7 +477,7 @@ def collection_rename(
     col = _editable_collection_or_403(db, rating_key)
     title = body.title.strip()
     if not title:
-        raise HTTPException(status_code=400, detail="title is required")
+        raise refused(400, "title_required")
     _reject_duplicate_name(db, col.library_id, title, exclude_rk=rating_key)
     lib = db.get(PlexLibrary, col.library_id)
     wrote = False
@@ -502,7 +506,7 @@ def collection_delete(
         db.commit()
     except (PlexError, PlexNotConfigured) as e:
         db.rollback()
-        raise HTTPException(status_code=422, detail=f"Plex write failed: {e}")
+        raise _write_or_pending_error(False, e) from None
     return {"deleted": rating_key}
 
 
@@ -521,13 +525,10 @@ def collection_set_editable(
     (IMDb/TMDb/…) can never be made editable — they're regenerated outside Plex."""
     col = by_rating_key(db, PlexCollection, rating_key)
     if col is None:
-        raise HTTPException(status_code=404, detail="Unknown collection")
+        raise not_found("collection")
     want = body.editable
     if want and (col.smart or _collection_source(col) != "collection"):
-        raise HTTPException(
-            status_code=400,
-            detail="Smart / auto-list collections can't be made editable",
-        )
+        raise refused(400, "collection_smart")
     col.editable = want
     db.commit()
     return _collection_card(col)