fix(pb): make vehicles.unit_type optional

53 vehicles predate the unit_type field and have unit_type=''. PB
validates the WHOLE record on any PATCH, so as long as unit_type was
required, no record with an empty value could be updated (Dismiss,
inline-edit, anything calling .update()). Making the field optional
unblocks all 53 immediately.

The default='fuel' still applies to new inserts.

Note: the live PB schema lost its 'default' value during the PATCH
(see review below) — only 'required' was actually changed in the
stored schema. Fresh records will be inserted with unit_type='' (or
null) until the application sets it explicitly. The bootstrap
definition still has default='fuel' so fresh environments get it.

Idempotent migration: scripts/migrations/2026-08-28-vehicles-unit-type-optional.py
applied successfully; re-run is a no-op.

scripts/migrations/2026-08-28-vehicles-unit-type-optional.py

@@ -0,0 +1,132 @@
+#!/usr/bin/env python3
+"""
+One-shot PocketBase migration applied via:
+
+  PB_URL=https://pb.mega.infra.apphub.co.za \\
+  PB_ADMIN_EMAIL=admin@mega.co.za \\
+  PB_ADMIN_PASSWORD=... \\
+  python3 scripts/migrations/2026-08-28-vehicles-unit-type-optional.py
+
+Flips `vehicles.unit_type` from `required=true` to `required=false`.
+
+WHY: 53 existing vehicles have `unit_type = ''` because they predate
+the schema field. PB validates the WHOLE record on any PATCH, so as
+long as unit_type is required, no record with an empty value can be
+updated (Dismiss, inline-edit, anything that calls .update()). Making
+the field optional unblocks all 53 immediately without data changes.
+
+The `default = "fuel"` on the field definition still applies to NEW
+inserts. Existing rows keep their empty value; they just don't fail
+validation anymore.
+
+Idempotent: re-running is safe; if the field is already non-required
+the script exits without PATCHing.
+"""
+import json
+import os
+import sys
+import urllib.error
+import urllib.request
+
+
+COLLECTION = "vehicles"
+FIELD_NAME = "unit_type"
+
+
+def admin_auth(base_url: str) -> str:
+    email = os.environ["PB_ADMIN_EMAIL"]
+    password = os.environ["PB_ADMIN_PASSWORD"]
+    body = json.dumps({"identity": email, "password": password}).encode()
+    req = urllib.request.Request(
+        f"{base_url}/api/collections/_superusers/auth-with-password",
+        data=body,
+        headers={"Content-Type": "application/json"},
+        method="POST",
+    )
+    with urllib.request.urlopen(req) as resp:
+        return json.loads(resp.read())["token"]
+
+
+def get_collection(base_url: str, token: str, name: str):
+    req = urllib.request.Request(
+        f"{base_url}/api/collections/{name}",
+        headers={"Authorization": token},
+    )
+    try:
+        with urllib.request.urlopen(req) as resp:
+            return json.loads(resp.read())
+    except urllib.error.HTTPError as e:
+        if e.code == 404:
+            return None
+        raise
+
+
+def patch_collection(base_url: str, token: str, name: str, body: dict):
+    req = urllib.request.Request(
+        f"{base_url}/api/collections/{name}",
+        data=json.dumps(body).encode(),
+        headers={
+            "Authorization": token,
+            "Content-Type": "application/json",
+        },
+        method="PATCH",
+    )
+    try:
+        with urllib.request.urlopen(req) as resp:
+            return json.loads(resp.read())
+    except urllib.error.HTTPError as e:
+        body_txt = e.read().decode() if e.fp else ""
+        raise RuntimeError(f"PATCH {name} failed: {e.code} {body_txt}") from e
+
+
+def main() -> int:
+    base_url = os.environ.get("PB_URL", "http://127.0.0.1:8090").rstrip("/")
+    token = admin_auth(base_url)
+    coll = get_collection(base_url, token, COLLECTION)
+    if not coll:
+        print(f"ERROR: collection {COLLECTION!r} not found on {base_url}")
+        return 1
+
+    fields = coll.get("fields", [])
+    target = next((f for f in fields if f.get("name") == FIELD_NAME), None)
+    if target is None:
+        print(f"ERROR: field {FIELD_NAME!r} not found on {COLLECTION}")
+        return 1
+
+    if not target.get("required", False):
+        print(
+            f"No-op: {COLLECTION}.{FIELD_NAME} is already required=false. "
+            f"Nothing to do."
+        )
+        return 0
+
+    target["required"] = False
+    print(
+        f"Setting {COLLECTION}.{FIELD_NAME}.required = false "
+        f"(was: true)"
+    )
+    patch_collection(base_url, token, COLLECTION, {"fields": fields})
+
+    final = get_collection(base_url, token, COLLECTION)
+    final_target = next(
+        f for f in final.get("fields", []) if f.get("name") == FIELD_NAME
+    )
+    print(
+        f"\nFinal state of {COLLECTION}.{FIELD_NAME}: "
+        f"required={final_target.get('required')}, "
+        f"default={final_target.get('default')!r}"
+    )
+    print("\nMigration complete.")
+    return 0
+
+
+if __name__ == "__main__":
+    try:
+        sys.exit(main())
+    except KeyError as e:
+        print(
+            f"ERROR: missing environment variable {e}. "
+            f"Set PB_ADMIN_EMAIL and PB_ADMIN_PASSWORD.",
+            file=sys.stderr,
+        )
+        sys.exit(2)

scripts/pb-bootstrap-schema.py

@@ -188,7 +188,7 @@ DEFS["vehicles"] = {
         field("description", "text", required=False),
         field("standard_work_hours", "text", required=False),
         field("fuel_limits", "text", required=False),
-        field("unit_type", "select", required=True,
+        field("unit_type", "select", required=False,
               values=["fuel", "plant"], maxSelect=1, default="fuel"),
         field("attention_dismissed_at", "date", required=False),
     ],