feat: add User.name field (rescoped per ADR 006)

[martinydeAI]

Summary

Add the User Doctrine entity — the application's first persistent
identity — with the minimum set of fields needed by upcoming auth and
authorisation work.

Updated per ADR 006 (#60 / #61). The original scope listed an
active boolean and a domainManager boolean. Both are superseded
by ADR 006 and have been removed from this issue:

• active → replaced by a UserStatus enum (pending | approved | blocked), filed as its own issue (feat: UserStatus enum and User.status field #83).
• domainManager → replaced by the ROLE_DOMAIN_MANAGER role on
  the existing User.roles column, filed as its own issue (feat: ROLE_DOMAIN_MANAGER, ROLE_ADMIN, role_hierarchy, and domain-scoped voter #84).

This issue ships only name on top of the auth fields (email,
password, roles) inherited from the #2 login work. The status
column and the role wiring land on top in #83 / #84.

Fields

Field	Type	Purpose
name	string	Display name.

The entity will grow (kommune association, organisation FK, etc.) as
related issues land — keep this PR focused on name.

Scope

• App\Entity\User under src/Entity/ gains a name column with
  matching getter / setter (@ORM\Column(length: 255), not null).
• App\Repository\UserRepository already exists; no change here
  unless the test suite needs a small helper.
• Doctrine migration adding the name column.
• Smoke tests for the new field (UserTest round-trip + repository
  reload).
• CHANGELOG.md entry under ## [Unreleased] / Added.

Out of scope

• status enum and the status column — see feat: UserStatus enum and User.status field #83.
• ROLE_DOMAIN_MANAGER, role hierarchy, voter — see feat: ROLE_DOMAIN_MANAGER, ROLE_ADMIN, role_hierarchy, and domain-scoped voter #84.
• Any UI for editing name — that's part of User profile and account management #13 (User profile).
• Anything beyond name on the entity itself.

Related issues

• User login #2 — User login (provides the auth fields this issue extends).
• User roles and permissions #12 — User roles and permissions (the broader RBAC story; feat: ROLE_DOMAIN_MANAGER, ROLE_ADMIN, role_hierarchy, and domain-scoped voter #84
  delivers the first concrete role set).
• User profile and account management #13 — User profile and account management (UI for editing name).
• Define assistant data model #14 — Define assistant data model (Assistant likely carries a FK
  to User).
• Add PHPUnit test suite and CI workflow #31 — Add PHPUnit test suite and CI workflow.
• Decide on backend admin/CRUD tooling (EasyAdmin?) and form conventions #39 — Decide on backend admin/CRUD tooling (affects how User is
  administered).
• Decide on user registration, approval, and account-state model #60 / docs: add ADR 004 — user registration, approval, and account state #61 — ADR 006 deciding the scope of this rescope.
• feat: UserStatus enum and User.status field #83 — UserStatus enum + status column (lands on top of this).
• feat: ROLE_DOMAIN_MANAGER, ROLE_ADMIN, role_hierarchy, and domain-scoped voter #84 — ROLE_DOMAIN_MANAGER + role hierarchy + voter (lands on top
  of this).

Acceptance

• App\Entity\User exposes a name: string field with matching
  getter / setter.
• Doctrine migration adds the name column to the existing
  user table.
• Tests cover the new field (entity round-trip + repository
  persist / reload).
• CHANGELOG.md updated under ## [Unreleased] / Added.
• task coding-standards-check and task test-coverage (100%
  gate) both green.

[martinydeAI]

Heads-up: ADR 004 (#60, PR #61) supersedes the active boolean
planned here. The new model is a status enum on User
(pending | approved | blocked).

When this issue is implemented the entity should ship with
name, domainManager, and status — not active. See the
"Implication for #45" section of
ADR 004
for context.

[martinydeAI]

Second update from ADR 004: domainManager: bool is also superseded
— by the role ROLE_DOMAIN_MANAGER on the existing User.roles
column. Promote / demote is just toggling the role in the array,
and the manager's scope is derived from the part of their own email
address after the @.

Net effect on this issue: when the User entity here is implemented it
ships with only name on top of the auth fields from #2 / PR #59.
Neither active nor domainManager are introduced. See the
"Domain manager — a role, not a flag" and updated "Implication for
#45" sections of
ADR 004.