The adoption pass reads the runs inside its window, not the whole archive (#1607)

[suleimansh]

Closes #1607 — its last open note.

The cost

The cloud-work adoption pass wants the settled web runs of the last 48 hours. It asked the store for every archived run the project has ever had, parsed each one, and then let waitingRuns drop everything outside the window. That ran every ten minutes, forever, against a directory that only grows.

The change

An archived run is filed as <id>.json, and an id is the run's start time — so the filename already dates the record. listAgents takes an optional since (epoch ms) and answers it from the directory listing: a name that parses as one of our ids and is older than the cutoff is skipped before it is ever opened.

Measured on this repo's real archive, through the compiled code with a counting read seam:

full history: 162 records, 162 reads
48h window:   4 records,   4 reads

Two edges, both deliberate

• A name that does not parse as one of our ids is read as before. An id handed in from outside is not a date, and rejecting it unread would hide it from every caller that passes a window. There is a test for exactly this.
• The id is allocated when a run is spawned; startedAt is written when it first opens its store. So the name can be the older of the two by the length of a spawn, and a caller filtering on startedAt sees a record leave the window at most that much early — against a window measured in days.

The history list, the boot reconcile and every by-id lookup pass no since and read the archive whole, as they must.

Verification

• 1528/1528 pass.
• Both new tests were validated by breaking the code they guard: with the filename filter neutered and the window cutoff replaced by 0, exactly those two fail and nothing else does.