refactor(ui): adopt react-hook-form for account & settings forms

[luannmoreira]

What

Migrates the Account & settings form group to react-hook-form: the Profile
edit and change-password drawers, the Settings rename-namespace drawer, and the
admin SAML configuration drawer. Next step of the incremental migration tracked
in shellhub-io/team#152, following the SignUp and auth-form migrations.

Why

Each of these forms hand-threaded useState + onChange + per-field error
computation. Reusing the established RHF field wrappers and resolver-adapter
pattern removes that boilerplate and gives the SAML drawer real validation
structure and its first tests.

Changes

• fields/rhf/FormTextareaField: new useController-bound wrapper over a raw
  <textarea> (INPUT styling + className override, aria-invalid /
  aria-describedby), for the SAML certificate field. Joins the existing three
  wrappers.
• Profile: EditProfileDrawer and ChangePasswordDrawer moved to useForm
  with per-form resolvers (editProfileResolver, changePasswordResolver)
  reusing the existing validators (relocated into pages/profile/validate.ts
  unchanged, preserving messages). Recovery-email remains a cross-field rule —
  changing the primary email re-triggers it via trigger("recoveryEmail"). The
  profile payload is still built from changed fields only (dirtyFields).
• Settings: EditNameDrawer bound via useController over the existing
  NamespaceNameField, delegating to validateNamespaceName (wrapped ?? true
  so a valid name is not treated as invalid).
• SAML: SamlConfigDrawer moved to useForm with samlResolver replicating
  the metadata-URL-vs-manual conditional rules; useWatch drives the mode UI and
  buildBody was refactored to a pure function of the form values.
• Validation UX preserved: errors surface only once a field diverges from its
  saved value; empty required fields gate the submit button rather than showing an
  error. Form-level server errors use RHF root errors; drawer-local UI state
  (SAML showAdvanced, change-password success) resets on open via
  useResetOnOpen.
• Out of scope (not validated forms, untouched): the Settings session-recording
  and device-auto-accept toggles, the delete-confirm and leave dialogs, and the
  Profile delete-account dialogs.

Testing

vitest in the ui container — full console suite green (2701 tests). New
coverage: FormTextareaField, the three resolvers, and the previously-untested
SamlConfigDrawer (metadata to manual toggle, per-mode required-field gating, and
the submit payload for both modes). Worth probing: the recovery-email cross-field
path (change only the primary email and confirm the recovery-email error appears)
and that prefilled edit drawers show no error until a field is changed.

[github-actions]

Claude finished @luannmoreira's task in 7m 59s —— View job

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Code Review Complete

Reviewed 17 files across code quality, security, testing, language patterns, and architecture. 1 inline issue posted (1 high).

The migration itself is clean: buildBody for SAML is byte-for-byte identical to the old request shape, the dirtyFields-based profile payload correctly reproduces the old per-field diffing, ChangePasswordDrawer and EditNameDrawer preserve their required-field gating, and the resolver adapters return the correct { values, errors } shape. No security regressions (SAML cert/metadata handling and password flow are unchanged; textarea binds through React with no raw HTML).

The one real finding is a validation regression in editProfileResolver where clearing a required field (Name/Username/Email) leaves the Save button enabled — see the inline comment for details and two fix options.

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[luannmoreira]

Superseded by #6619, which reorganizes this work into the umbrella react-hook-form migration PR (team#152) with one commit per topic (Profile, Settings, SAML config). Same diff; continuing there.