Fix MatchesEventFilter regression and update fuzzing docs

- Change structural guard in MatchesEventFilter to return false (reject)
  instead of true (pass through) when event JSON is missing params object.
  This matches the old inline behavior where missing fields resolved to
  empty strings and failed filter comparison.
- Update doc/fuzzing.md to remove references to deleted fuzz targets:
  TranslateKeys, ValidateQuickPickChoices, ValidateSettingsJson.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Author: yeelam-gordon

doc/fuzzing.md

@@ -9,8 +9,8 @@ OneFuzz for continuous coverage.
 
 | Project | Path | Targets |
 |---------|------|---------|
-| **WtcliFuzzer** | `src/tools/wtcli/ft_fuzzer/` | `TranslateKeys`, `BuildSendEventJson`, `MatchesEventFilter` |
-| **ProtocolFuzzer** | `src/cascadia/TerminalProtocol/ft_fuzzer/` | `ClassifySendEvent`, `ParseSplitDirection`, `ClassifyPaneOutputSource`, `ValidateQuickPickChoices`, `ValidateSettingsJson` |
+| **WtcliFuzzer** | `src/tools/wtcli/ft_fuzzer/` | `BuildSendEventJson`, `MatchesEventFilter` |
+| **ProtocolFuzzer** | `src/cascadia/TerminalProtocol/ft_fuzzer/` | `ClassifySendEvent`, `ParseSplitDirection`, `ClassifyPaneOutputSource` |
 | **OpenConsoleFuzzer** | `src/host/ft_fuzzer/` | `WriteCharsLegacy` (original host fuzzer) |
 
 Each project contains:

src/tools/wtcli/wtcli_functions.h

@@ -77,9 +77,11 @@ namespace wtcli
         }
 
         // Event JSON must be an object with a "params" object inside.
+        // Reject structurally invalid events when filters are active —
+        // missing fields can't match any filter.
         if (!ev.isObject() || !ev.isMember("params") || !ev["params"].isObject())
         {
-            return true;
+            return false;
         }
 
         if (!sessionIdFilter.empty())