Makes the N-file array-write case usable as the real-controller hardware gate:
AB_LEGACY_ARRAY_WRITE_BASE names the first of six consecutive words (default
N7:1), each word is read first and written back in a finally, and the
neighbours are verified per word with coalescing off. Live-run green on
ab_server slc500/micrologix/plc5 x libplctag/native (39/39), and with a moved
base (N7:3).
Refs #738
Claude-Session: https://claude.ai/code/session_01Ub9hGmYLQvn9XETzw7CMsT
Review 07 U10 (user decision: implement array encode now). Both runtimes
encoded a scalar for an array tag: an int[] threw InvalidCastException into
BadTypeMismatch + Degraded, a scalar wrote element 0 natively, and libplctag's
SetInt32(0, ..) re-sent the stale last-read buffer for elements 1..n-1.
IAbLegacyTagRuntime gains EncodeArray; both runtimes write every element at
the element width (Int/AnalogInt 2 bytes, Long/Float 4). The driver converts
the written value before any runtime exists: each element is converted, not
exact-matched (ScadaBridge writes int[] to Int16 nodes), a length other than
the tag's element count is BadOutOfRange, an overflowing element is
BadOutOfRange, a non-array or non-numeric payload is BadTypeMismatch, and a Bit
array (bit-packed words; an encode would clobber neighbour bits) is
BadNotSupported. None of these touch health or the wire. Adds an env-gated
ab_server round trip for an N-file array write.
Refs #738
Claude-Session: https://claude.ai/code/session_01Ub9hGmYLQvn9XETzw7CMsT
Joseph Doherty