feat: custom fields per project

Text, number, date or option-list fields defined in the project settings
(archived, never removed; their type is fixed once saved). Tickets hold
them, edited in the side panel, listed under the title and filtered by
option in the list view; also over GraphQL, REST (?field=ID:value) and MCP.

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

libs/api/tracker/presenters/src/lib/graphql/inputs.ts

@@ -1,5 +1,6 @@
 import { Field, ID, InputType, Int } from '@nestjs/graphql';
 import {
+  CustomFieldType,
   IssueLinkType,
   IssuePriority,
   ProjectRole,
@@ -95,6 +96,16 @@ export class ProjectMemberInput {
   role!: ProjectRole;
 }
 
+@InputType({ description: "A custom field's value; null or '' clears it" })
+export class CustomFieldValueInput {
+  @Field() @Matches(SETTING_ID) fieldId!: string;
+  @Field(() => String, { nullable: true })
+  @IsOptional()
+  @IsString()
+  @MaxLength(500)
+  value?: string | null;
+}
+
 @InputType({ isAbstract: true })
 abstract class IssueFieldsInput {
   @Field(() => String, { nullable: true })
@@ -146,6 +157,17 @@ abstract class IssueFieldsInput {
   @Field(() => String, { nullable: true }) @IsOptional() @IsISO8601() dueDate?:
     | string
     | null;
+
+  @Field(() => [CustomFieldValueInput], {
+    nullable: true,
+    description: 'Only the fields to change',
+  })
+  @IsOptional()
+  @IsArray()
+  @ArrayMaxSize(30)
+  @ValidateNested({ each: true })
+  @Type(() => CustomFieldValueInput)
+  customFields?: CustomFieldValueInput[];
 }
 
 @InputType()
@@ -537,6 +559,16 @@ export class IssueFilterInput {
   @IsOptional()
   @Matches(/^\d{4}-\d{2}-\d{2}$/)
   dueTo?: string;
+  @Field(() => [CustomFieldValueInput], {
+    nullable: true,
+    description: 'Only tickets holding these custom values',
+  })
+  @IsOptional()
+  @IsArray()
+  @ArrayMaxSize(30)
+  @ValidateNested({ each: true })
+  @Type(() => CustomFieldValueInput)
+  customFields?: CustomFieldValueInput[];
   @Field(() => IssueSort, { nullable: true, defaultValue: IssueSort.RECENT })
   @IsOptional()
   @IsEnum(IssueSort)
@@ -656,6 +688,23 @@ export class AreaOptionInput {
   @Field({ defaultValue: false }) @IsBoolean() archived!: boolean;
 }
 
+@InputType()
+export class CustomFieldDefinitionInput {
+  @Field() @Matches(SETTING_ID) id!: string;
+  @Field() @IsString() @MinLength(1) @MaxLength(40) name!: string;
+  @Field(() => CustomFieldType) @IsEnum(CustomFieldType) type!: CustomFieldType;
+  @Field(() => [String], {
+    defaultValue: [],
+    description: 'The choices of a SELECT field',
+  })
+  @IsArray()
+  @ArrayMaxSize(50)
+  @IsString({ each: true })
+  @MaxLength(60, { each: true })
+  options!: string[];
+  @Field({ defaultValue: false }) @IsBoolean() archived!: boolean;
+}
+
 @InputType({
   description:
     'The whole configuration (replaces the previous one). Statuses go in board order.',
@@ -688,6 +737,17 @@ export class ProjectSettingsInput {
   @ValidateNested({ each: true })
   @Type(() => AreaOptionInput)
   areas!: AreaOptionInput[];
+
+  @Field(() => [CustomFieldDefinitionInput], {
+    nullable: true,
+    description: 'Absent: unchanged. Fields cannot be removed: archive them.',
+  })
+  @IsOptional()
+  @IsArray()
+  @ArrayMaxSize(30)
+  @ValidateNested({ each: true })
+  @Type(() => CustomFieldDefinitionInput)
+  customFields?: CustomFieldDefinitionInput[];
 }
 
 @InputType({