feat(structures): add Region/Delegation/Structure schema + seed (ADR-0027 PR 1)

Schema (Prisma): three new public-schema models per ADR-0027 -
Region (INSEE code PK), Delegation (dept code PK + regionCode FK),
Structure (portal-internal code PK + kind discriminator + nullable
unique finess/siret/codePaie + nullable delegationCode FK).

Migration: hand-written, matches the style of init_audit_schema and
users_directory. DDL + CHECK constraint on Structure.kind mirroring
STRUCTURE_KINDS + indexes + inline seed (Region 75 Nouvelle-Aquitaine,
Delegation 33 Gironde, structures 0330800013 + 0330800021 medico-social
Bordeaux/Merignac + siege APF national). Seed is the minimum the 19
test-tenant personas reference; ADR-0029's cascade sync supersedes it
when it ships.

Catalogue (TypeScript): apps/portal-bff/src/structures/structure-kind.ts
exports STRUCTURE_KINDS as const + StructureKind type union +
isStructureKind type guard. Jest spec covers catalogue content,
type guard, narrowing.

Drift gate: extended to scan property-literal "kind: 'X'" expressions
in files that import from structure-kind.ts. Three-layer defense
in depth for Structure.kind = TS type union + Postgres CHECK +
CI gate. 22 spec tests passing.

No consumer code yet - PrismaScopeResolver that dereferences
Structure.code from UserScope.value lives in ADR-0026 PR 2, which
depends on this PR landing first.

Reviewer heads-up: schema.prisma already has a User model (ADR-0020
user-directory cache); ADR-0026 PR 1 introduces a different User
(UUID PK + Person FK). Naming collision flagged for that PR to
resolve - not touched here.

scripts/check-catalogue-drift.spec.mjs

@@ -15,6 +15,8 @@ import { tmpdir } from 'node:os';
 import { join } from 'node:path';
 import {
   extractCatalogues,
+  extractStructureKinds,
+  findStructureKindViolationsInFile,
   findViolationsInFile,
   scanWorkspace,
 } from './check-catalogue-drift.mjs';
@@ -46,6 +48,17 @@ function makeFixture({ files }) {
     ] as const;
     `,
   );
+  mkdirSync(join(root, 'apps/portal-bff/src/structures'), { recursive: true });
+  writeFileSync(
+    join(root, 'apps/portal-bff/src/structures/structure-kind.ts'),
+    `export const STRUCTURE_KINDS = [
+      'medico_social',
+      'antenne',
+      'siege',
+    ] as const;
+    export type StructureKind = (typeof STRUCTURE_KINDS)[number];
+    `,
+  );
   for (const [relativePath, contents] of Object.entries(files)) {
     const full = join(root, relativePath);
     mkdirSync(join(full, '..'), { recursive: true });
@@ -160,6 +173,95 @@ describe('findViolationsInFile', () => {
   });
 });
 
+describe('extractStructureKinds', () => {
+  it('reads the STRUCTURE_KINDS catalogue from structure-kind.ts', () => {
+    const root = makeFixture({ files: {} });
+    const kinds = extractStructureKinds(
+      join(root, 'apps/portal-bff/src/structures/structure-kind.ts'),
+    );
+    assert.deepEqual([...kinds].sort(), ['antenne', 'medico_social', 'siege']);
+  });
+
+  it('throws when the constant is missing', () => {
+    const root = mkdtempSync(join(tmpdir(), 'drift-fixture-'));
+    mkdirSync(join(root, 'apps/portal-bff/src/structures'), { recursive: true });
+    writeFileSync(
+      join(root, 'apps/portal-bff/src/structures/structure-kind.ts'),
+      `export const NOT_STRUCTURE_KINDS = ['foo'] as const;\n`,
+    );
+    assert.throws(
+      () =>
+        extractStructureKinds(join(root, 'apps/portal-bff/src/structures/structure-kind.ts')),
+      /STRUCTURE_KINDS/,
+    );
+  });
+});
+
+describe('findStructureKindViolationsInFile', () => {
+  const validKinds = new Set(['medico_social', 'antenne', 'siege']);
+
+  it('skips files that do not import structure-kind (would false-positive)', () => {
+    // `kind: 'whatever'` is a common pattern on unrelated objects.
+    // Without the import filter, every such literal would be flagged.
+    const text = `
+      const event = { kind: 'somenoise', payload: {} };
+    `;
+    const violations = findStructureKindViolationsInFile('virtual.ts', validKinds, text);
+    assert.equal(violations.length, 0);
+  });
+
+  it('returns no violations when every kind literal is in the catalogue', () => {
+    const text = `
+      import type { StructureKind } from '../structures/structure-kind';
+      const a = { kind: 'medico_social' as StructureKind };
+      const b = { kind: 'siege' as StructureKind };
+    `;
+    const violations = findStructureKindViolationsInFile('virtual.ts', validKinds, text);
+    assert.equal(violations.length, 0);
+  });
+
+  it('flags every kind literal not in the catalogue', () => {
+    const text = `
+      import { STRUCTURE_KINDS } from '../structures/structure-kind';
+      const a = { kind: 'medico_social' };
+      const b = { kind: 'medical_social' };
+      const c = { kind: 'sanitaire' };
+    `;
+    const violations = findStructureKindViolationsInFile('virtual.ts', validKinds, text);
+    assert.equal(violations.length, 2);
+    const values = violations.map((v) => v.value).sort();
+    assert.deepEqual(values, ['medical_social', 'sanitaire']);
+    assert.equal(violations[0].callee, 'Structure.kind');
+    assert.equal(violations[0].catalogue, 'STRUCTURE_KINDS');
+  });
+
+  it('skips non-literal initialisers (variable indirection)', () => {
+    // The TypeScript signature catches this at compile time when the
+    // target type is `StructureKind` — the gate is best-effort here.
+    const text = `
+      import { STRUCTURE_KINDS } from '../structures/structure-kind';
+      const k = 'something';
+      const a = { kind: k };
+    `;
+    const violations = findStructureKindViolationsInFile('virtual.ts', validKinds, text);
+    assert.equal(violations.length, 0);
+  });
+
+  it('reports line and column of the offending literal', () => {
+    const text = [
+      `import { STRUCTURE_KINDS } from '../structures/structure-kind';`,
+      `const x = {`,
+      `  kind: 'rogue-kind',`,
+      `};`,
+    ].join('\n');
+    const violations = findStructureKindViolationsInFile('virtual.ts', validKinds, text);
+    assert.equal(violations.length, 1);
+    assert.equal(violations[0].line, 3);
+    // 'rogue-kind' literal starts at column 9 (0-indexed 8, +1 in the report).
+    assert.equal(violations[0].column, 9);
+  });
+});
+
 describe('scanWorkspace', () => {
   it('returns 0 violations on a clean fixture', () => {
     const root = makeFixture({
@@ -230,4 +332,26 @@ describe('scanWorkspace', () => {
     const { violations } = scanWorkspace(root);
     assert.equal(violations.length, 1);
   });
+
+  it('aggregates decorator + Structure.kind violations together', () => {
+    const root = makeFixture({
+      files: {
+        'apps/portal-bff/src/foo.ts': `
+          import { STRUCTURE_KINDS } from './structures/structure-kind';
+          @RequirePrivilege('Portal.Ghost') class Bad {}
+          const s = { kind: 'phantom_kind' };
+        `,
+      },
+    });
+    const { violations } = scanWorkspace(root);
+    assert.equal(violations.length, 2);
+    const values = violations.map((v) => v.value).sort();
+    assert.deepEqual(values, ['Portal.Ghost', 'phantom_kind']);
+  });
+
+  it('returns the structureKinds set alongside catalogues', () => {
+    const root = makeFixture({ files: {} });
+    const { structureKinds } = scanWorkspace(root);
+    assert.deepEqual([...structureKinds].sort(), ['antenne', 'medico_social', 'siege']);
+  });
 });