Spec #135: owner data-correction actions — Latest Chapter, series_url, Cover, orphan removal (#156)

Implements spec #135 (spec 2 of 4, derived from wayfinder map #114; decisions settled in #120/#121/#125/#131). Blocked-by #134 is merged, so this lands on `main`.

Four owner actions the dashboard can now perform, one ticket each:

- **#149** — Latest Chapter correction: one numeric input, overwritten by the next machine write.
- **#151** — Series URL repair: owner-typed, gated by the poller's own fetch gate.
- **#150 / #153 / #154** — Cover replacement: addresses derived from bytes (`#150`), a Forced Poll replaces the Cover while an ordinary pass still only fills a blank one (`#153`), and byte reclamation is one guarded helper, file first / covers row last (`#154`).
- **#155** — Orphan removal: one Series at a time, with the foreign key as the guard.

Plus **#152** — Latest Chapter provenance: one derived line naming the actor class, so an owner can tell a hand-edited number from a machine read.

- Migration `0015_latest_correction.sql` adds the correction/provenance columns; `0009` now derives cover addresses from bytes.
- ADR `0014-cover-addresses-from-bytes.md` records the address scheme.

Backend tests cover the store, poller, admin handlers, and web routes (`go test ./...`, needs Docker).

Reviewed-on: #156
Co-authored-by: Sulthan Zaki <sultankiki05@gmail.com>
Co-committed-by: Sulthan Zaki <sultankiki05@gmail.com>

backend/internal/latest/cover.go

@@ -174,7 +174,7 @@ func (f *TLSCoverFetcher) Fetch(ctx context.Context, sourceURL string) ([]byte,
 	return body, contentType, nil
 }
 
-// This gate deliberately differs from fetchableSeriesURL: cover hosts are
+// This gate deliberately differs from FetchableSeriesURL: cover hosts are
 // site-independent CDNs, so a Site host allowlist would reject valid covers.
 func (f *TLSCoverFetcher) validateURL(ctx context.Context, u *url.URL) error {
 	if u == nil || u.Scheme != "https" || u.Host == "" || u.User != nil {