fix: bench-refinement batch for the 0.4 line (#58, #60, #63, #64, #65)

Fixes from the Bench refinement milestone that exist on 0.4, one commit each. Merge without squashing.

• deps: urllib3 2.8.0, tornado 6.5.10, anyio 4.14.2 — nine advisories failed the audit gate on every line (supersedes !34 (closed))
• #63 (closed) Plan() builds in linear time (10^5 steps: ms, was ~44 s)
• #60 (closed) a device's own TimeoutError keeps its message; only the server budget answers "Operation timed out"
• #64 (closed) a plot caption wraps instead of setting the panel's minimum width
• #58 (closed) client field test calls operations with arguments: schema defaults, generated values for required ones (from describe), new optional op_payloads
• #65 (closed) plesty-sdk locked at its exp instead of 0.3.5, so gate 8 diffs this line against 0.4.1, not 0.5.0

Each fix has a test that fails without it. All gates pass locally with the current SDK. CHANGELOG under Unreleased.

Once merged: maintain/0.4 → maintain/0.5 (cut from v0.5.0) → exp.