Adds <summary>/<param>/<returns>/<inheritdoc> where missing and removes
project bookkeeping IDs (task/tracking refs) from shipped code comments,
so the docs read cleanly and CommentChecker is quiet except for known
false positives (PLC/protocol terms, event/IEqualityComparer inheritdoc).
Doc/comment-only; no logic changed; solution builds clean.
Introduces Driver.S7.Contracts (dependency-free POCO project) and moves
S7DriverOptions / S7ProbeOptions / S7TagDefinition / S7DataType into it.
Adds S7CpuType enum mirroring S7.Net.CpuType exactly (7 values with
explicit integer codes). Runtime S7CpuTypeMap bridges S7CpuType →
S7.Net.CpuType at the single Plc construction site in S7Driver.InitializeAsync.
S7DriverFactoryExtensions and S7CommandBase updated to use S7CpuType; test
files updated to match (S7_1500Profile, S7DriverScaffoldTests). AdminUI can
now reference Driver.S7.Contracts without pulling in S7netplus.