feat: statuses and ticket types take any colour from a colour picker

Settings shows a native colour picker (the palette as suggestions)
instead of the list of eleven names. The API takes a palette name, as
before, or any #rrggbb; picking a palette colour still saves its name,
so it keeps its hand-made dark version. A free colour gets one variant
per theme, computed with the `color` library (moved towards white or
black until it contrasts 3:1 with the surface) and applied with
light-dark(): a pale yellow darkens on white, a navy lightens on dark.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

apps/api/openapi.json

@@ -12763,22 +12763,6 @@
           "CANCELLED"
         ]
       },
-      "SettingColor": {
-        "type": "string",
-        "enum": [
-          "slate",
-          "stone",
-          "violet",
-          "blue",
-          "sky",
-          "teal",
-          "green",
-          "amber",
-          "orange",
-          "red",
-          "pink"
-        ]
-      },
       "WorkflowStatusDto": {
         "type": "object",
         "properties": {
@@ -12799,11 +12783,9 @@
             ]
           },
           "color": {
-            "allOf": [
-              {
-                "$ref": "#/components/schemas/SettingColor"
-              }
-            ]
+            "type": "string",
+            "description": "A palette colour (follows the theme) or #rrggbb",
+            "example": "violet"
           },
           "requiresReason": {
             "type": "boolean",
@@ -12907,11 +12889,9 @@
             ]
           },
           "color": {
-            "allOf": [
-              {
-                "$ref": "#/components/schemas/SettingColor"
-              }
-            ]
+            "type": "string",
+            "description": "A palette colour (follows the theme) or #rrggbb",
+            "example": "violet"
           },
           "archived": {
             "type": "boolean"
@@ -13262,11 +13242,10 @@
             ]
           },
           "color": {
-            "allOf": [
-              {
-                "$ref": "#/components/schemas/SettingColor"
-              }
-            ]
+            "type": "string",
+            "description": "A palette colour (slate, stone, violet, blue, sky, teal, green, amber, orange, red, pink), which follows the theme, or any #rrggbb",
+            "example": "#7c3aed",
+            "pattern": "^(slate|stone|violet|blue|sky|teal|green|amber|orange|red|pink|#[0-9a-fA-F]{6})$"
           },
           "requiresReason": {
             "type": "boolean",
@@ -13351,11 +13330,10 @@
             ]
           },
           "color": {
-            "allOf": [
-              {
-                "$ref": "#/components/schemas/SettingColor"
-              }
-            ]
+            "type": "string",
+            "description": "A palette colour (slate, stone, violet, blue, sky, teal, green, amber, orange, red, pink), which follows the theme, or any #rrggbb",
+            "example": "#7c3aed",
+            "pattern": "^(slate|stone|violet|blue|sky|teal|green|amber|orange|red|pink|#[0-9a-fA-F]{6})$"
           },
           "archived": {
             "type": "boolean",