fix(linear-static-3d-euler-beam): reject CLI option values

docs/implementation-plans/linear-static-3d-euler-beam-implementation-report.md

@@ -1289,3 +1289,42 @@
   Step 27 can consume only its `physics_evidence` after Step 26 passes.
 - concerns: none; no critical implementation, environment, numerical, or
   upstream-contract blocker remains.
+
+### Step 24 Review Fix Round 1 — option-token output rejection
+
+- review_trigger: the approved CLI contract classifies repeated `--output`
+  and every unknown option as usage error exit 2. The original three-argument
+  parser treated the value position as an arbitrary nonempty path, so an
+  option token could advance into input analysis instead.
+- RED-repeated-option: after adding
+  `{missingInput,"--output","--output"}` to the existing exact
+  `LinearStaticCli.ReturnsEveryExactExitCodeAndOrderedDiagnostic` test,
+  `cmake --build .harness/build --config Debug --target
+  fesa_integration_tests` exited 0 and the focused CTest exited 1. Actual exit
+  was 3 and stderr contained no `cli-usage`, rather than expected exit 2.
+- GREEN-repeated-option: rejecting the literal repeated token made the same
+  focused test pass 1/1.
+- RED-unknown-option: the reviewer then identified the general unknown-option
+  case. Adding `{missingInput,"--output","--bogus"}` before broadening the
+  production condition again produced build exit 0 and focused CTest exit 1;
+  actual exit was 3 with no `cli-usage`.
+- production_fix: explicit output form now requires a nonempty third argument
+  that does not begin with `-`. Both a repeated known option and an unknown
+  option token are rejected before any input or output access, while ordinary
+  output paths retain the approved behavior.
+- GREEN-focused: rebuilding `fesa_integration_tests` exited 0 under `/W4 /WX`;
+  the unchanged exact focused test passed 1/1 with both option cases pinned.
+- independent_review: Critical 0, unresolved Important 0. The reviewer reran
+  exact Step 24 10/10, discovery 83, full 83/83, comparison 176 rows/16
+  metrics passed, and reference diff/status clean.
+- remaining_minor: the test-only comparator independently pins float64 result
+  file types but relies on the Step 23 writer self-check/full-suite schema test
+  for exact uint64 endianness and every compound member file dtype/UTF-8. This
+  is defense-in-depth negative coverage, not a reproducible approved-pipeline
+  false pass.
+- remaining_minor: the inherited diagnostic sorter is not a literal
+  implementation of future multi-source declaration/internal-ID ordering, but
+  no V0 single-input CLI misordering is reproducible.
+- remaining_minor: the Step 23 `libmmd.dll` guard remains unconditional across
+  alternate HDF5 targets; it is correct for the approved shared-HDF5
+  environment and is an external portability limitation.