Wire wait stats config as single source of truth (#215 part 2)

- Trim WaitStats.json from 52 to 44 entries — drop server-level / instance-
  level waits (THREADPOOL, BACKUPIO, BACKUPBUFFER, HADR_SYNC_COMMIT,
  DBMIRROR_DBM_EVENT, SQLTRACE_BUFFER_FLUSH) and connection-setup waits
  (PREEMPTIVE_OS_AUTHENTICATIONOPS, PREEMPTIVE_OS_LOOKUPACCOUNTSID) that
  don't appear in plan XML's <WaitStats> element.

- Populate attributes 6-8 (showWaitCount, showAverageWaitTime,
  timeCalculationModel) from existing tool behavior. Attributes 9-12
  (applicable operators, descriptions, URLs, internal comment) remain
  null — those need domain expertise.

- Add WaitStatsConfig loader (PlanViewer.Core.Services.WaitStatsConfig)
  that reads the JSON from an embedded resource at first access and
  caches by name (case-insensitive). Resource lookup is suffix-based so
  the file works whether embedded under PlanViewer.Core.* or
  PlanViewer.Web.* manifest prefixes.

- BenefitScorer.IsExternalWait now delegates to WaitStatsConfig.IsExternal.
  Lookup misses fall back to false, preserving prior default for unknown
  waits. EmitWaitStatWarnings drops the WaitStatsKnowledge dependency
  entirely.

- Delete WaitStatsKnowledge.cs — its ShowEffectiveLatency flag was the
  only structural data and is now sourced from
  WaitStatsConfig.ShowAverageWaitTime. Description/HowToFix were
  intentionally empty since #215 D3, so nothing of substance is lost.

- Wire embedded resource into PlanViewer.Core.csproj and link it +
  WaitStatsConfig.cs into PlanViewer.Web.csproj (which links Core
  source files rather than referencing the project).

All 75 Core tests pass; Core, App, and Web all build clean.

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

Author: erikdarlingdata

src/PlanViewer.Core/PlanViewer.Core.csproj

@@ -21,6 +21,7 @@
 
   <ItemGroup>
     <EmbeddedResource Include="Resources\PlanIcons\*.png" />
+    <EmbeddedResource Include="Resources\WaitStats.json" />
   </ItemGroup>
 
 </Project>