fix(metadata): stop concatenating series and issue number into comicvine title (#861)

* fix(metadata): stop concatenating series and issue number into comicvine title

ComicVine search and auto-fill set title to a synthesized "Series #N -
Name" string instead of the issue's own name, inconsistent with how
ComicInfo.xml's <Title> is used elsewhere in the app (issue title only,
series and issue number in their own fields). title now carries just
the issue name, falling back to "<series> #<issue>" only when ComicVine
has no name for that issue.

The concatenated format is genuinely useful for telling issues apart
in the search-results list, so a new optional displayTitle field
preserves that exact UX there, populated only by the ComicVine mapper.
It's display-only and never read by any metadata-apply path, so the
list keeps its current look while the metadata that actually gets
persisted is cleanly separated.

filterAndRank now scores candidates against displayTitle when present,
falling back to title otherwise, so shortening title doesn't drop named
issues when users search by series name. Since displayTitle is only
ever set by the ComicVine mapper, this reproduces today's exact
ranking behavior for ComicVine and leaves every other provider
untouched.

Closes #841

* fix(metadata): leave comic titles unset when comicvine has no issue name

Address review feedback on the comicvine title mapping.

Issue #841 asked for the issue name alone, or nothing when comicvine has none for that issue.
Falling back to "<series> #<issue>" kept writing a synthesized title for unnamed issues, which
is the common case in a comic run, so the ComicInfo round trip only held for named issues. Make
MetadataCandidate.title optional and leave it unset instead: the pipeline already skips absent
fields, and the client already omits diff rows whose candidate value is empty, so an unnamed
issue now leaves any existing title alone. displayTitle still labels those candidates in the UI.

Comic titles no longer parse as "<series> #<issue>", which is how ComicVineProvider decided
between its precise volume-plus-issue search and the far looser general issue search. Carry
seriesName and seriesIndex on MetadataSearchParams and prefer them when the title does not
parse, so a refresh or a re-search of an already-matched comic keeps the structured path. A
title that does parse still wins, since that is a user typing an explicit target.

Also apply the display title in the diff panel's within-provider result picker, which renders
only when a provider returned several candidates and so needs the issue number most; match the
skip patterns against the same string that gets scored rather than title alone; and drop the
redundant cover alt text on the result card, where the headline already names the result.

---------

Co-authored-by: neon <18559658+neonsolstice@users.noreply.github.com>

packages/types/src/metadata-fetch.ts

@@ -62,7 +62,9 @@ export interface MetadataCandidate {
   provider: MetadataProviderKey;
   providerId: string;
   hardcoverEditionId?: string;
-  title: string;
+  /** Absent when the provider has no title of its own for this record, e.g. an unnamed comic issue. */
+  title?: string;
+  displayTitle?: string;
   subtitle?: string;
   authors?: string[];
   description?: string;