IssueTracker auto-completes active sessions when openIssues fetch is incomplete

[dhilgaertner]

What happened

Opened the app and found three sessions that should be active had been moved to
completed:

• citadel-134-sensor-framework (citadel#134 — still OPEN)
• crow-66-launch-announcement (crow#66 — issue no longer resolvable)
• citadel-98-cost-tracking-pricing (citadel#98 — still OPEN)

All three share updated_at: 2026-04-16T17:16:26Z, i.e. one IssueTracker run
flipped them together. A fourth session (ontology-prototype-1) was untouched.

Why I think it's the auto-completer

autoCompleteFinishedSessions in Sources/Crow/App/IssueTracker.swift:1013
works by set-difference: any candidate session whose ticketURL isn't in the
fetched openIssues list is treated as finished. Two branches are unsafe when
the fetch is partial:

• Line 1042-1043: PR is missing from viewerPRs → falls back to
  "absence == done" and marks completed.
• Line 1048-1051: no PR link + issue not in openIssues → marks completed.

Neither branch distinguishes "issue is closed" from "fetch returned nothing /
returned a partial page / was rate-limited." Issue #173 (closed same day,
2026-04-16) was about GraphQL rate-limit exhaustion here, so a degraded
response on that date is plausible.

Repro hypothesis

1. Have >=1 active session with an OPEN assigned GitHub issue.
2. Force fetchOpenIssues / viewerPRs to return an empty or truncated list
   (rate-limit, network error swallowed, pagination cutoff, scope change).
3. autoCompleteFinishedSessions runs → every active session with a ticketURL
   not in the (bad) list is marked completed.

Suggested fix directions

• Treat an empty / errored openIssues result as a no-op, not as "everything
  finished." Propagate fetch success/failure into the auto-complete step.
• Require positive evidence of closure before completing: either the issue is
  present in openIssues and marked CLOSED, or a dedicated per-ticket state
  query confirms it. Remove the absence == done fallback.
• Add a floor check: if the fetched open-issue count is 0 while we have N
  candidate sessions with tickets, skip auto-complete and log a warning.
• Add a unit test for autoCompleteFinishedSessions covering the
  partial-fetch case.

Recovery

Reset the three sessions:

crow set-status --session 27664893-E932-4AB3-97D6-7C8A6F997829 active
crow set-status --session EC8B5E7F-25A6-4E9A-A321-5087B01D32CA active
crow set-status --session 1D802104-9921-49EA-81DC-2D42F4AD2C6D active

Related: #173.