feat(client-archive): smart-archive backend foundation (dossier + archive + restore)

The first slice of the smart-archive project. Replaces the dumb DELETE
client flow with a deliberate "look before you leap" pattern:

- New columns on clients: archived_by, archive_reason, archive_metadata
  (jsonb capturing every decision made during archive, so restore can
  attempt reversal). Migration 0043.
- client-archive-dossier.service builds a structured snapshot of "what's
  at stake" for a given client: pipeline interests, berths under offer
  (with next-in-line interests for the notification), yachts owned,
  active reservations, outstanding invoices, signed/in-flight Documenso
  envelopes, portal user, company memberships. Classifies the client as
  low-stakes or high-stakes based on pipeline stage (HIGH_STAKES_STAGES
  = deposit_10pct + later) so the bulk wizard knows which clients to
  prompt individually.
- client-archive.service.archiveClientWithDecisions takes the operator's
  decisions and applies them in a single transaction. Persists the
  decision log into archive_metadata for restore. Auto-handles portal
  user revocation + company membership end-dating; everything else is
  caller-driven. Surfaces external cleanups (Documenso void) for the
  caller to queue.
- client-restore.service.getRestoreDossier classifies each persisted
  decision as autoReversible / reversibleWithPrompt / locked based on
  the current state of the world (berth still available? new owner has
  active interests on the yacht? etc). restoreClientWithSelections
  applies reversals + un-archives the client.
- 4 API routes wire the services to HTTP. The existing /restore
  endpoint is upgraded to use the smart restore but stays
  backwards-compatible: clients archived before this feature have no
  archive_metadata so the dossier returns empty, and a POST with no
  body just un-archives them — same as before.

UI work + bulk variant + hard-delete + Documenso cleanup queueing land
in follow-on commits.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

src/lib/db/schema/clients.ts

@@ -31,6 +31,18 @@ export const clients = pgTable(
     source: text('source'), // website, manual, referral, broker
     sourceDetails: text('source_details'),
     archivedAt: timestamp('archived_at', { withTimezone: true }),
+    /** Better-auth user id of the operator who archived this client. */
+    archivedBy: text('archived_by'),
+    /** Free-text reason captured at archive time. Required when archiving a
+     *  client at deposit_10pct or later (compliance trail). Optional when
+     *  archiving an early-stage lead. */
+    archiveReason: text('archive_reason'),
+    /** Per-decision metadata captured during smart-archive flow. Used by
+     *  the restore wizard to attempt reversal. Shape:
+     *    { decisions: Array<{ kind, refId, ...specifics }>, decidedAt, decidedBy }
+     *  See src/lib/services/client-archive.service.ts for the canonical
+     *  payload schema. */
+    archiveMetadata: jsonb('archive_metadata'),
     /** When this client was merged into another (the "loser" of a dedup
      *  merge), this points at the surviving client. Used by the
      *  /admin/duplicates review queue to redirect any stragglers, and by