feat(web,store,latest): forced poll — Check now stamps a Series for the next Lane pass (#146)

The control writes series.force_poll_at (column landed in migration 0014)
and never commands the poller: pending is derived as force_poll_at >
latest_checked_at and self-clears because the check stamp is written before
the fetch. The due query's forced flag overrides the rest cutoff, the
Sighting-deferral and finished-only clauses, jumps the queue, and wakes a
sleeping browser Lane; it never overrides an empty series_url, the Bookmarks
join, the refusal backoff, the sidecar-down skip or the Lane gap.

ADRs: 0013-commands-through-the-database.

docs/adr/0013-commands-through-the-database.md

@@ -0,0 +1,60 @@
+# ADR-0013: Commands through the database
+
+Date: 2026-08-22
+Status: accepted
+
+## Decision
+
+Owner interventions are **facts about rows, never commands to the poller**.
+*Check now* (`POST /admin/series/{key}/poll`) writes one stamp —
+`series.force_poll_at`, unix ms, zero meaning never asked (the column landed
+in migration 0014) — and the poller's next pass reads it through
+`Store.DueForLatestCheck`. The control never signals the running process, so
+a request survives a restart, and the whole surface is testable with no
+poller running at all.
+
+**Pending is derived, never stored**: a Series is pending while
+`force_poll_at > latest_checked_at`. It self-clears with no second write and
+no sweeper because the check stamp is written *before* the fetch (the same
+"attempted" discipline as ADR-0010) — the first attempt ends the pending
+state whatever the attempt returns. There is no expiry: a request the Lane
+never reaches keeps ageing in the UI, and an old pending marker is itself the
+evidence that a Lane is stuck. Writing again re-stamps the request time; the
+write is idempotent.
+
+**Queue-jump rules.** A forced Series overrides exactly three gates in the
+due query: the rest cutoff, the Sighting-deferral clause and the finished-only
+bucket, and it sorts to the front of the queue
+(`ORDER BY forced DESC, reader_count DESC, latest_checked_at ASC`). It never
+overrides an empty `series_url` (nothing to fetch), the Bookmarks join (a
+Series no Reader holds has no consumer for the result), the Lane's refusal
+backoff, the sidecar-down skip, or the Lane's gap — the last three are
+poller-side gates the query cannot see and must not. The one pass-level gate
+a forced Series does open is the browser wake threshold: a human asking wakes
+a sleeping Chrome, where the thresholds exist to stop the machine waking
+itself for one unattended check. If the home machine is off, nothing happens
+and the request ages visibly, which is correct.
+
+Rejected: zeroing the check stamp as the force signal. It would corrupt the
+never-checked and stale counts the landing page exists to show, and make a
+pending marker impossible.
+
+## Why
+
+A stuck-looking Series previously waited for its turn in the Lane's hour, and
+there was no way to ask for one check sooner. A direct poller command would
+have been lost on every restart and untestable without a running poller; a
+row the poller already reads is neither. Deriving pending from the two stamps
+keeps the flag honest across restarts and makes the mechanism two column
+writes and three query clauses instead of a state machine.
+
+## Constraints
+
+- The finished-status clause the force flag overrides is today's Lifecycle
+  test; a later spec in this series deletes it wholesale rather than amending
+  it, so the clause stays as it stands.
+- The control is unconfirmed (it takes nothing away) and renders no
+  `.confirm-row`; it is hidden on a Series with no `series_url` and on an
+  orphan — the same pair the due query refuses to override.
+- The answer to a press is the freshly rendered row, so the figures describe
+  the state after the press.