Reach the wrong-case apposition fallback

The fallback that lets an apposition or parenthesis in the wrong case
parse with an error tag ("Ég ræddi við forsætisráðherra (Sigmundur
Davíð)") was defined under the misspelt name Svigainnihald_* and thus
never referenced, although GreynirCorrect still has the handler for
its AðvörunSvigaInnihaldNl node.

Attach it as the last, lowest-priority alternative of SvigaInnihald
via a per-case helper. A separate definition block would have gotten
top priority and pruned the correct readings, since the priority
counter of a block is not shared with the generic definition.

On the 1000-sentence baseline 2 trees change, both improved (a
parenthesis "( átta )" now attaches as an apposition instead of
forcing a heading analysis). Engine and GreynirCorrect suites pass.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

Author: vthorsteinsson

src/reynir/Greynir.grammar

@@ -5459,12 +5459,15 @@ SvigaInnihald/tala/fall/kyn →
     > Nl/fall               # Sama fall en ekki sama tala
     > SvigaInnihaldFsRuna
     > HreinYfirsetning
-
-# Ef ekki finnst sama fall og tala, prófa almennan nafnlið
-Svigainnihald_nf/tala/pers/kyn → AðvörunSvigaInnihaldNl/fallxnf
-Svigainnihald_þf/tala/pers/kyn → AðvörunSvigaInnihaldNl/fallxþf
-Svigainnihald_þgf/tala/pers/kyn → AðvörunSvigaInnihaldNl/fallxþgf
-Svigainnihald_ef/tala/pers/kyn → AðvörunSvigaInnihaldNl/fallxef
+    # Ef ekki finnst sama fall og tala, prófa nafnlið í öðru falli (villa).
+    # Þetta verður að vera aftast í forgangsröðinni hér, þar sem sérstök
+    # skilgreining (SvigaInnihald_nf/tala/kyn → ...) fengi hæsta forgang.
+    > SvigaInnihaldAnnaðFall/fall
+
+SvigaInnihaldAnnaðFall_nf → AðvörunSvigaInnihaldNl/fallxnf
+SvigaInnihaldAnnaðFall_þf → AðvörunSvigaInnihaldNl/fallxþf
+SvigaInnihaldAnnaðFall_þgf → AðvörunSvigaInnihaldNl/fallxþgf
+SvigaInnihaldAnnaðFall_ef → AðvörunSvigaInnihaldNl/fallxef
 
 # Árabil nota en-dash