mbproxy: strip historical phase/wave/plan references from source comments

Comments described the *history* of how the code arrived (phase numbers,
wave IDs, review IDs, dated TODOs) instead of what it does today. That
scaffolding rotted as the codebase evolved. Cleaned 60 source files +
.gitignore; behaviour unchanged (387/387 tests still pass).

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

mbproxy/src/Mbproxy/Proxy/Cache/CacheKey.cs

@@ -4,10 +4,10 @@ namespace Mbproxy.Proxy.Cache;
 
 /// <summary>
 /// Hash key for the per-PLC <see cref="ResponseCache"/>. Structurally identical to
-/// Phase 10's <see cref="CoalescingKey"/> — both keys discriminate the same dimensions
-/// (UnitId, FunctionCode, StartAddress, Quantity), but the two type aliases live in
-/// different namespaces so the two phases can evolve independently without one shaping
-/// the other's API surface.
+/// the read-coalescing <see cref="CoalescingKey"/> — both keys discriminate the same
+/// dimensions (UnitId, FunctionCode, StartAddress, Quantity), but the two type aliases
+/// live in different namespaces so the cache and the coalescer can evolve independently
+/// without one shaping the other's API surface.
 ///
 /// <para><b>Equality semantics:</b> record-struct value equality. FC03 and FC04 produce
 /// different keys for the same address (different Modbus tables); different