Remove dead FsFeatDefnUi class and stale JumpToRecord comments

[mark-sil]

Summary

Dead-code removal ahead of the JumpToRecord Mediator-to-PubSub conversion (follow-up in the spirit of #1032/#1044). Removes one of the seven synchronous SendMessage("JumpToRecord") senders as dead code before the conversion starts.

• Delete Src/FdoUi/FsFeatDefnUi.cs — the entire class is unreachable (see analysis below), including its SendMessage("JumpToRecord").
• FdoUiCore.cs — remove the unreachable case FsFeatDefnTags.kClassId: from CmObjectUi.CreateNewUiObject.
• MasterPhonFeatDlgListener.cs / MasterInflFeatDlgListener.cs — delete commented-out //m_mediator.SendMessage("JumpToRecord", ...) lines and fold the comment lines that referred to them into a single accurate line.

Why FsFeatDefnUi is unreachable

• Its only external reference is the FsFeatDefnTags.kClassId case in CmObjectUi.CreateNewUiObject (FdoUiCore.cs).
• The only call chain into that switch is DTMenuHandler → Slice.HandleInsertCommand → Slice.InsertObject → CmObjectUi.CreateNewUiObject. (The one other HandleInsertCommand caller, InflAffixTemplateMenuHandler, is inside #if Later — compiled out.)
• No configuration XML anywhere in DistFiles passes className="FsFeatDefn" to an insert command.
• Even if XML did, Slice.InsertObject returns -1 for abstract classes before calling CreateNewUiObject — FsFeatDefn is abstract in the LCM model; MoForm is the only abstract class it special-cases (remapped to a concrete allomorph class).
• MakeUi uses an explicit compiled switch (no reflection-by-name) and never constructs FsFeatDefnUi.
• User-customized or extension-supplied XML cannot reach it either: the abstract-class gate lives in compiled code and the compiled LCM model, so a hand-added DataTreeInsert command with className="FsFeatDefn" was already a silent no-op before this change and behaves identically after it.

What stopped happening, and why each disappearance is safe

• Nothing user-visible stopped. The deleted code could not execute on any path, shipped or customized.
• Inserting inflection/phonological features still works through CmdInsertClosedFeature / CmdInsertComplexFeature / CmdInsertPhonologicalClosedFeature via RecordClerk.OnInsertItemInVector → the DialogInsertItemInVector Pub/Sub event → the Master*FeatDlgListeners, which are unaffected (their live BroadcastMessageUntilHandled("JumpToRecord", ...) sends remain).

Validation

• .\build.ps1 -SkipNative: Build succeeded, 0 errors; FdoUi.dll and MorphologyEditorDll.dll rebuilt.
• Re-grepped: no remaining references to FsFeatDefnUi or FsFeatDefnTags in Src/FdoUi.
• No csproj edit needed (FdoUi is an SDK-style project with file globbing).

🤖 Generated with Claude Code

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This change is 

[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 33.10%. Comparing base (f713635) to head (382f07a).

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #1045   +/-   ##
=======================================
  Coverage   33.10%   33.10%           
=======================================
  Files        1201     1200    -1     
  Lines      277959   277937   -22     
  Branches    37130    37128    -2     
=======================================
+ Hits        92018    92019    +1     
+ Misses     158146   158126   -20     
+ Partials    27795    27792    -3     

Files with missing lines	Coverage Δ
Src/FdoUi/FdoUiCore.cs	8.73% <ø> (+<0.01%)	⬆️
...rc/LexText/Morphology/MasterInflFeatDlgListener.cs	0.00% <ø> (ø)
...rc/LexText/Morphology/MasterPhonFeatDlgListener.cs	0.00% <ø> (ø)

... and 1 file with indirect coverage changes

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[jasonleenaylor]

@jasonleenaylor reviewed 4 files and all commit messages, and made 1 comment.
Reviewable status: complete! all files reviewed, all discussions resolved (waiting on mark-sil).