V4.6 Phase 5: UI boundaries and duplication

Fixes the three ui.instructions.md violations recorded as [HIGH-07] and extracts
the page-level duplication catalogued in review section 4.

Boundary violations
- jobs_page no longer imports session_scope or manages a transaction.
  store.create_document_job and store.create_job_for_document accept an optional
  session_factory and open their own session scope when the caller supplies
  neither a session nor a factory.
- sources_page no longer calls sqlalchemy.inspect. SourceService
  .read_latest_execution_attempt now returns a LatestExecutionAttempt read model
  carrying a plain transport_body_deferred flag, so ORM loader state stays inside
  the service. Rendered output is unchanged.
- Deletes ui/components/document_panzoom.py, its export, and its CSS. The
  component was exported but used by no page. Pan-zoom is planned for a clean
  reintroduction in V4.7 alongside the other photo/image work.

Extracted duplication
- ui/components/media_urls.py: pure upload-URL resolution taking upload_dir and
  base_url, replacing two identical ~60-line copies in sources_page and
  people_page.
- ui/components/guards.py: parse-then-render-terminal-message, replacing 28
  hand-written guard labels across five pages.
- ui/components/confirm_delete.py: the blocked-dependency notice and the
  delete/cancel action row, from four delete pages.
- ui/components/upload_panel.py: the auto-uploading file picker, from three
  pages. Source accept lists now derive from services.source_media
  .SOURCE_EXTENSIONS instead of being hard-coded.
- ui/components/table/registry.py: the two hand-rolled label-registry tables on
  the settings page now go through build_table, which gained selection and
  rows_per_page options.
- ui/components/formatters.py gains parse_uuid and parse_iso_date, replacing
  five and two private copies.
- ui/runtime.py owns resolve_runtime_settings, replacing three copies and
  removing get_settings from every page module.

[LOW-05]
- Upload handlers are annotated with events.UploadEventArguments.
- The Document and Person form builders return DocumentFormFields and
  PersonFormFields dataclasses instead of dict[str, Any].

Verification
- tests/test_ui_boundaries.py asserts no page imports a session scope, a session
  factory, get_settings, sqlalchemy, or sqlmodel, and that no component imports
  request or application state.
- 275 passed, 4 skipped. ruff check clean.

Findings: HIGH-07, LOW-05

Co-authored-by: Copilot App <[email protected]>

src/transcription/ui/components/media_urls.py

@@ -0,0 +1,74 @@
+"""Pure resolution of stored media paths into browser-reachable upload URLs."""
+
+from __future__ import annotations
+
+from pathlib import Path
+from urllib.parse import quote
+
+_ABSOLUTE_SCHEMES = ("http://", "https://", "data:")
+_UPLOAD_ROUTE_PREFIX = "/uploads/"
+
+
+def absolute_upload_url(path: str, *, base_url: str) -> str:
+    """Join an application-relative upload path onto the request base URL."""
+    base = base_url.rstrip("/")
+    normalized_path = path if path.startswith("/") else f"/{path}"
+    return f"{base}{normalized_path}"
+
+
+def resolve_media_url(path: str | None, *, upload_dir: Path, base_url: str) -> str | None:
+    """Map a stored media path onto a served upload URL.
+
+    Stored paths have accumulated several shapes over the life of the schema:
+    absolute filesystem paths, paths relative to the working directory, paths
+    relative to the upload root, and paths that already carry an upload route.
+    All of them must still resolve, so each shape is tried in turn.
+    """
+    candidate = (path or "").strip()
+    if not candidate:
+        return None
+
+    normalized = candidate.replace("\\", "/")
+    lowered = normalized.casefold()
+    if lowered.startswith(_ABSOLUTE_SCHEMES):
+        return normalized
+    if normalized.startswith(_UPLOAD_ROUTE_PREFIX):
+        return absolute_upload_url(normalized, base_url=base_url)
+
+    resolved_upload_dir = upload_dir.resolve()
+    path_obj = Path(candidate)
+
+    if path_obj.is_absolute():
+        absolute_candidates = [path_obj.resolve()]
+    else:
+        absolute_candidates = [
+            (Path.cwd() / path_obj).resolve(),
+            (resolved_upload_dir / path_obj).resolve(),
+        ]
+
+    for absolute_candidate in absolute_candidates:
+        try:
+            relative = absolute_candidate.relative_to(resolved_upload_dir).as_posix()
+        except ValueError:
+            continue
+        return absolute_upload_url(f"/uploads/{quote(relative)}", base_url=base_url)
+
+    upload_name = resolved_upload_dir.name.casefold()
+    normalized_parts = Path(normalized).parts
+    lowered_parts = [part.casefold() for part in normalized_parts]
+    if upload_name in lowered_parts:
+        index = lowered_parts.index(upload_name)
+        relative = Path(*normalized_parts[index + 1 :]).as_posix()
+        if relative:
+            return absolute_upload_url(f"/uploads/{quote(relative)}", base_url=base_url)
+
+    if lowered.startswith("uploads/"):
+        return absolute_upload_url(f"/{normalized}", base_url=base_url)
+    if lowered.startswith("data/"):
+        relative = normalized.split("/", 1)[1] if "/" in normalized else ""
+        if relative:
+            return absolute_upload_url(f"/uploads/{quote(relative)}", base_url=base_url)
+    if lowered.startswith(("documents/", "persons/")):
+        return absolute_upload_url(f"/uploads/{quote(normalized)}", base_url=base_url)
+
+    return absolute_upload_url(f"/uploads/{quote(path_obj.name)}", base_url=base_url)