feat(video): redact transcript text from logs and durable memory (#12150 P1) (#12427)

P1 of #12150: transcript text no longer reaches call logs or durable memory in the clear.

Reconciled on merge — the two persisted-requestBody assertions were failing, and the failure signature was misleading enough to be worth recording. They reported "expected: true, actual: false", which reads like the redaction not applying. It was not: pollForCallLog waited at most 120 tries x 20ms = 2.4s for the asynchronous SQLite write, then returned null, so assert.ok(row) failed before any redaction assertion ran. The observed durations were 5253ms and 4467ms against that 2.4s ceiling — a starved runner, not a leak. The control test failing alongside the positive one was the tell: a real redaction defect would break one direction, not both.

Replaced the fixed try count with a 30s wall-clock deadline: far past any healthy write, still bounded, and a fast machine still returns on the first pass. A privacy test should not depend on how busy the box is.

Verified: 4/4 three consecutive times under synthetic load, and 3/3 unloaded beforehand. Note the synthetic load reached ~7, below the ~38 where the original failure appeared, but the budget is now 12.5x larger and deadline-based rather than count-based.