Admin dashboard: pages, Lane observability, poll pass log, per-Series intervention (#134) (#148)

Spec #134, all ten tickets. Closes #134.

## What ships

The admin surface becomes four bookmarkable addresses behind one nav row, and Lane observability stops dying with the process.

- **#138** `/admin` splits into Overview, Lanes, Readers, Series, each a real route with the active tab underlined.
- **#139** `poll_passes` and `poll_lanes` land as durable tables with their store surface.
- **#140** cross-Series admin read model, with the privacy boundary in the projection: the Reader id that raised a Latest Chapter never leaves the store package.
- **#141** the poller records exactly one pass row per exit, with a skip reason and outcome counts.
- **#142** Series list: eight hygiene filters, Site and Library narrowing, paging — all of it in the query string, so a filtered list is a bookmark.
- **#143** Overview: a three-state verdict line and a stats block where every non-zero figure links to the list that counts it.
- **#144** per-Series detail page, keyed by the `site:series_id` composite the rest of the system already uses.
- **#145** the Lanes page reads the database; the in-memory Lane state, `web.LaneReporter` and `latest.Status` are deleted.
- **#146** Forced Poll: *Check now* stamps `series.force_poll_at` and never commands the poller.
- **#147** pause and resume one Site's Lane, with a mandatory 1h/6h/24h expiry.

## Shape of the design

Two decisions carry the rest. **Commands go through the database, never at the poller**: both *Check now* and a Lane pause write a row the next pass reads, so they survive a restart and the whole surface stays testable with no poller running. And **pending is derived, never stored** — the request stamp being newer than the check stamp — which self-clears on the check stamp with no second write and no sweeper, because the check stamp is written before the fetch.

ADRs: `docs/adr/0012-persisted-lane-state.md`, `docs/adr/0013-commands-through-the-database.md`.

## Verification

`go test ./...` green on the merged base (`264839e`), all packages, Docker-backed. `gofmt -l` and `go vet` clean.

Every ticket was reviewed on both axes (`cr-spec` + `cr-standards`) before merge.

## Known, non-blocking

- **#143** the verdict ignores never-reported Lanes when other Lanes have reported, and the per-Site table lists Sites that have Series rather than the whole registry. The ticket prose asks for eight hygiene figures per Site; the design mock and the landed `.tbl.sites` grid both say six columns, and the mock won.
- **#146** two `SeriesPage` scans per press instead of a keyed read — `ponytail:`-commented in-tree with the upgrade path.
- **#147** a paused Site with no pass row yet renders no row and so no control, since the Lanes page lists Sites that have passed.
- **#141** a sibling browser Lane declining at the top of a pass records as `sidecar-down`. Specified deliberately; the later spec in this series settles it.

Reviewed-on: #148
Co-authored-by: Sulthan Zaki <sultankiki05@gmail.com>
Co-committed-by: Sulthan Zaki <sultankiki05@gmail.com>

backend/internal/web/admin_series_detail.go

@@ -0,0 +1,126 @@
+package web
+
+import (
+	"log"
+	"net/http"
+	"strconv"
+	"strings"
+	"time"
+
+	"bookmarkmanager/backend/internal/store"
+)
+
+// seriesDetailView is one Series' page as the owner sees it: strings and
+// flags, every judgement made here, the template left to print. ReaderCount
+// is the only figure that crosses the privacy boundary — the owner learns how
+// many Readers hold the Series, never which Reader reads what.
+type seriesDetailView struct {
+	Key  string // "<site>:<series_id>", the page's address and the Series' identity
+	Site string
+	Kind string
+	// Title, Cover and Chapter come from the shared Series row; the Cover is
+	// the wire URL of the stored bytes, "" before any exist.
+	Title   string
+	Cover   string
+	Chapter string // Latest Chapter number, or "—" before the first capture
+	Checked string // how long ago the poller last checked, or "never"
+	Readers int
+
+	// Marks, one per hygiene fact, rendered only while it holds.
+	Unpollable     bool // no SeriesURL to fetch
+	NoCover        bool
+	Orphan         bool // no Reader holds the Series
+	SightingRaised bool // a Reader's Sighting set the Latest Chapter
+
+	// Poll is the Check now control and the pending marker (issue #146): the
+	// same derivation and visibility as the list row. CanPoll is false on a
+	// Series with no page to fetch and on an orphan; Pending is derived —
+	// the request stamp is newer than the check stamp — and Requested is its
+	// ageing label.
+	CanPoll   bool
+	Pending   bool
+	Requested string
+}
+
+// adminSeriesDetail renders one Series' page, keyed by the composite
+// "<site>:<series_id>" the list row already shows. The row is read through
+// the list's own SeriesPage read narrowed to the key's Site: the admin
+// projection is the privacy boundary, and a dedicated single-row read would
+// be a second definition of it.
+func (h *Handler) adminSeriesDetail(w http.ResponseWriter, r *http.Request) {
+	site, seriesID, ok := strings.Cut(r.PathValue("key"), ":")
+	if !ok || site == "" || seriesID == "" {
+		http.NotFound(w, r)
+		return
+	}
+	a, found, err := h.adminSeriesByKey(site, seriesID)
+	if err != nil {
+		log.Printf("series detail %s: %v", site+":"+seriesID, err)
+		http.Error(w, "internal error", http.StatusInternalServerError)
+		return
+	}
+	if !found {
+		http.NotFound(w, r)
+		return
+	}
+	h.renderAdmin(w, adminView{Page: "series-detail", Detail: h.seriesDetailView(a)})
+}
+
+// adminSeriesByKey reads one Series through the list's own SeriesPage read
+// narrowed to the key's Site: the admin projection is the privacy boundary,
+// and a dedicated single-row read would be a second definition of it. Absence
+// is reported with found=false, never an error.
+// ponytail: a page scan per keyed read, one query per page of the Site's rows
+// up to the window total; a keyed read alongside SeriesPage when the library
+// outgrows the page size.
+func (h *Handler) adminSeriesByKey(site, seriesID string) (store.AdminSeries, bool, error) {
+	seen := 0
+	for page := 1; ; page++ {
+		p, err := h.store.SeriesPage(store.SeriesFilter{Site: site, Page: page})
+		if err != nil {
+			return store.AdminSeries{}, false, err
+		}
+		seen += len(p.Rows)
+		for i := range p.Rows {
+			if p.Rows[i].SeriesID == seriesID {
+				return p.Rows[i], true, nil
+			}
+		}
+		if seen >= p.Total {
+			break
+		}
+	}
+	return store.AdminSeries{}, false, nil
+}
+
+// seriesDetailView shapes one AdminSeries row for display: every judgement in
+// Go, the template left to print strings and flags.
+func (h *Handler) seriesDetailView(a store.AdminSeries) seriesDetailView {
+	canPoll, pending, requested := pollState(a, time.Now())
+	v := seriesDetailView{
+		Key:            a.Key(),
+		Site:           a.Site,
+		Kind:           a.Kind,
+		Title:          a.Title,
+		Cover:          h.store.CoverWireURL(a.CoverAddress),
+		Readers:        a.ReaderCount,
+		Unpollable:     a.SeriesURL == "",
+		NoCover:        a.CoverAddress == "",
+		Orphan:         a.ReaderCount == 0,
+		SightingRaised: a.RaisedByReader,
+		CanPoll:        canPoll,
+		Pending:        pending,
+		Requested:      requested,
+	}
+	if a.LatestChapterNum == nil {
+		v.Chapter = "—"
+	} else {
+		v.Chapter = strconv.FormatFloat(*a.LatestChapterNum, 'f', -1, 64)
+	}
+	if a.LatestCheckedAt == 0 {
+		v.Checked = "never"
+	} else {
+		v.Checked = since(time.Now(), time.UnixMilli(a.LatestCheckedAt))
+	}
+	return v
+}