root: flag British spellings in cspell (#22821)

cspell's bundled en_US dictionary accepts British spellings (colour, behaviour, organise, ...) even with language en-US. Add a flagWords list covering the common -our/-ise/-yse/-re/-ce families so they are reported as forbidden words with the American spelling offered as a fix, plus ignore entries for upstream-spelled exceptions (PatternFly pf-m-grey, lit-analyse, analyse-phase).

MERGE LAST: failFast is on, so this rule must land only after the docs/backend/frontend cleanup PRs have merged, otherwise CI fails on pre-existing British spellings.

Co-authored-by: Playpen Agent <279763771+playpen-agent@users.noreply.github.com>

cspell.config.jsonc

@@ -81,6 +81,82 @@
         "cpp-compound-words"
     ],
     "allowCompoundWords": true,
+    // British spellings to reject in favor of American variants. The `->` form
+    // forbids the left word and offers the right word as the suggested fix.
+    "flagWords": [
+        // -our -> -or
+        "colour->color",
+        "colours->colors",
+        "coloured->colored",
+        "colouring->coloring",
+        "behaviour->behavior",
+        "behaviours->behaviors",
+        "favour->favor",
+        "favourite->favorite",
+        "favourites->favorites",
+        "flavour->flavor",
+        "flavours->flavors",
+        "honour->honor",
+        "labour->labor",
+        "neighbour->neighbor",
+        "neighbours->neighbors",
+        // -ise/-isation -> -ize/-ization
+        "organise->organize",
+        "organised->organized",
+        "organising->organizing",
+        "organisation->organization",
+        "initialise->initialize",
+        "initialised->initialized",
+        "initialising->initializing",
+        "initialisation->initialization",
+        "authorise->authorize",
+        "authorised->authorized",
+        "authorisation->authorization",
+        "customise->customize",
+        "customised->customized",
+        "customisation->customization",
+        "serialise->serialize",
+        "serialised->serialized",
+        "deserialise->deserialize",
+        "deserialised->deserialized",
+        "normalise->normalize",
+        "normalised->normalized",
+        "normalisation->normalization",
+        "synchronise->synchronize",
+        "synchronised->synchronized",
+        "optimise->optimize",
+        "optimised->optimized",
+        "optimisation->optimization",
+        "recognise->recognize",
+        "recognised->recognized",
+        "specialise->specialize",
+        "prioritise->prioritize",
+        "prioritised->prioritized",
+        "summarise->summarize",
+        "summarised->summarized",
+        "minimise->minimize",
+        "maximise->maximize",
+        "utilise->utilize",
+        "finalise->finalize",
+        "finalised->finalized",
+        // -yse -> -yze
+        "analyse->analyze",
+        "analysed->analyzed",
+        "analysing->analyzing",
+        // -re -> -er
+        "centre->center",
+        "centres->centers",
+        "centred->centered",
+        // -ce -> -se and misc
+        "licence->license",
+        "defence->defense",
+        "catalogue->catalog",
+        "dialogue->dialog",
+        "programme->program",
+        "grey->gray",
+        "artefact->artifact",
+        "artefacts->artifacts"
+    ],
     "patterns": [
         {
             "name": "EncodedURI",
@@ -128,6 +204,11 @@
         "\\w+l?ified\\b",
         // "ifying" suffix, e.g. "stringifying", "classifying".
         "\\w+l?ifying\\b",
+        // PatternFly's grey label modifier is spelled the British way upstream.
+        "pf-m-grey",
+        // External tool/path names that are spelled the British way upstream.
+        "lit-analyse",
+        "analyse-phase",
         "SpellCheckerIgnoreInDocSetting",
         "EncodedURI",
         "Urls",