feat(post-audit): Phase 3/6/7 schema foundations + bounce parser

Phase 3 — EOI override foundation (migration 0073):
- client_contacts/addresses/yachts get source + source_document_id
  with FK SET NULL on doc deletion. CHECK constraints enforce the
  allow-list of source values (manual/imported/eoi-custom-input or
  manual/imported/eoi-generated for yachts).
- documents.override_client_* + override_yacht_* columns mirror the
  AcroForm field set per docs/eoi-documenso-field-mapping.md. When
  NULL the canonical record value flows; when set, this document
  uses the override without touching the underlying record.
- Drizzle schema mirrors all new columns; numeric import added to
  documents schema for the yacht-dimensions override columns.

Phase 6 — IMAP bounce foundation (migration 0074):
- document_sends.bounce_status / bounce_reason / bounce_detected_at
  with bounce_status CHECK constraint (hard/soft/ooo).
- Partial index for the "show bounced sends" UI filter.
- New src/lib/email/bounce-parser.ts library — handles RFC 3464 DSN
  + Outlook NDR shapes + OOO auto-replies. Returns null recipient
  + 'unknown' class when shape isn't recognizable. Cron worker
  deferred to Phase 6b.

Phase 7 — PDF editor field-map types:
- New src/lib/templates/field-map.ts defines FieldMap shape with
  percent-coord positioning so placements survive page-size changes.
- Zod schemas for API boundary validation.
- validateFieldMapAgainstPageCount helper for the "new PDF upload"
  warning.
- No schema migration needed — existing document_templates.
  overlay_positions JSONB column accepts the new shape; the editor
  migrates legacy absolute-coord entries on first save.

Tests: 1374/1374 passing. tsc clean.

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

src/lib/templates/field-map.ts

@@ -0,0 +1,53 @@
+/**
+ * Phase 7 — PDF template editor field-map type definitions.
+ *
+ * The editor (deferred to 7.1/7.2) operates on the existing
+ * `document_templates.overlay_positions` JSONB column with the extended
+ * shape below. No schema migration is required — JSONB already accepts
+ * any shape; the only contract is the Zod validator on the API boundary.
+ *
+ * Coordinates are stored as percent of page width/height (0..1) so
+ * field placements survive page-size changes (A4 → US Letter etc.).
+ * The legacy overlay schema used absolute coords; the editor migrates
+ * those on first save by reading the source PDF's page dimensions.
+ */
+
+import { z } from 'zod';
+
+export const fieldMapEntrySchema = z.object({
+  /** Must match an entry in VALID_MERGE_TOKENS (validated at the API). */
+  token: z.string().min(1).max(100),
+  /** 1-indexed page number. */
+  page: z.number().int().min(1),
+  /** Percent of page width — top-left corner of the marker. */
+  x: z.number().min(0).max(1),
+  /** Percent of page height — top-left corner of the marker. */
+  y: z.number().min(0).max(1),
+  /** Percent width — defaults to 0.15 if omitted by an older editor. */
+  w: z.number().min(0).max(1).optional(),
+  /** Percent height — defaults to 0.04. */
+  h: z.number().min(0).max(1).optional(),
+  /** Optional explicit font size; otherwise auto-fit to the box. */
+  fontSize: z.number().int().min(6).max(72).optional(),
+});
+
+export const fieldMapSchema = z.array(fieldMapEntrySchema).max(500);
+
+export type FieldMapEntry = z.infer<typeof fieldMapEntrySchema>;
+export type FieldMap = z.infer<typeof fieldMapSchema>;
+
+/**
+ * Cross-validate a parsed field-map against the source PDF page count.
+ * The editor surfaces a warning when an upload truncates the page set
+ * (e.g. uploading a 3-page PDF over a 5-page template). Returns null
+ * when valid, or an error message describing the first out-of-range
+ * marker.
+ */
+export function validateFieldMapAgainstPageCount(map: FieldMap, pageCount: number): string | null {
+  for (const m of map) {
+    if (m.page > pageCount) {
+      return `Field "${m.token}" sits on page ${m.page} but the PDF only has ${pageCount} pages.`;
+    }
+  }
+  return null;
+}