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/web.go

@@ -50,9 +50,14 @@ type Handler struct {
 	// httpClient is the plain stdlib client that talks to Discord. It is not
 	// an injected interface: tests point APIBase at a stub server instead.
 	httpClient *http.Client
-	// lanes is the Poll Lane snapshot source the administrative page reads.
-	// Nil is a running deployment with no poller, not a bug.
-	lanes LaneReporter
+	// pollerEnabled reports whether latest-chapter polling is switched on in
+	// this deployment (LATEST_CHAPTER_POLL_ENABLED) and browserConfigured
+	// whether a browser sidecar is configured (BROWSER_WS_URL set). Both are
+	// deployment facts resolved by the composition root; the Lanes page (issue
+	// #145) reports them from config and derives reachability from the pass
+	// log rather than from whether a poller goroutine happened to start.
+	pollerEnabled     bool
+	browserConfigured bool
 }
 
 // listView is what every list-rendering template receives.
@@ -110,9 +115,11 @@ type loginView struct {
 // New parses every template up front so a broken one kills the process at
 // startup rather than the first request that touches it.
 //
-// lanes is the administrative page's window onto the running Poller; nil means
-// nothing is polling, which the page reports rather than hides.
-func New(s *store.Store, discord DiscordConfig, tokenKey []byte, mangaPath, novelPath string, lanes LaneReporter) (*Handler, error) {
+// pollerEnabled and browserConfigured are deployment facts the composition
+// root resolves from LATEST_CHAPTER_POLL_ENABLED and BROWSER_WS_URL: the Lanes
+// page (issue #145) reports them and derives browser reachability from the
+// pass log, so no running poller is wired through here at all.
+func New(s *store.Store, discord DiscordConfig, tokenKey []byte, mangaPath, novelPath string, pollerEnabled, browserConfigured bool) (*Handler, error) {
 	tmpl, err := template.ParseFS(templateFS, "templates/*.html")
 	if err != nil {
 		return nil, err
@@ -127,7 +134,8 @@ func New(s *store.Store, discord DiscordConfig, tokenKey []byte, mangaPath, nove
 		states:              newOAuthStates(),
 		limiter:             session.NewLoginLimiter(),
 		httpClient:          &http.Client{Timeout: discordTimeout},
-		lanes:               lanes,
+		pollerEnabled:       pollerEnabled,
+		browserConfigured:   browserConfigured,
 	}, nil
 }