fix(parties): skip nameless suppliers and customers in the party backfill (#2174)

* fix(parties): skip nameless suppliers and customers in the party backfill

The substrate migration failed on prod at the backfill: three rows (one
supplier, two customers) have an empty name and ensure_party refuses a
nameless party. The file never applied there, so it is corrected in place
rather than chased with a migration that could not run before it. Rows
without a name keep party_id NULL; the suggestion pipeline names them.

Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>

* fix(parties): ensure_party writes only under the caller's own identity

Authenticated callers must pass their own user id; the service role
(auth.uid() NULL: migrations, MCP, cron) may act for another user. Same
guard as apply_party_suggestions and decide_parties. Superagent P2 on
#2172.

Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>

---------

Co-authored-by: Jakob Wennberg <311770904+jakobwennberg-oss@users.noreply.github.com>
Co-authored-by: Claude Fable 5.1 <noreply@anthropic.com>

DECISIONS.md

@@ -1500,3 +1500,4 @@ One line per decision: `[YYYY-MM-DD] <decision>: <why>`. Appended by agents and
 [2026-09-02] Bank-sync cooldown is a durable lease column (bank_connections.sync_lease_until, migration 20260902150000) claimed with one conditional UPDATE, not a process-local attempt map: the security scan on PR #2165 showed the map is bypassed by a second serverless instance or a cold start, so two agent calls could each bill Enable Banking. A column add was chosen over reusing extension_data because PostgREST cannot express an atomic conditional upsert there; the nightly cron deliberately ignores the lease.
 [2026-09-02] Grok links carry auth=required like the claude.ai link (#2159), decided from a live test: on the lazy URL Grok's connector dialog listed all 150+ tools and never opened the sign-in, so it reads the 200 probe as an authless server exactly as claude.ai does. The flag lives in one helper (mcpServerUrl / sideDoorServerUrl in lib/onboarding/checklist.ts) so the settings row, the onboarding side door and the deep link cannot drift; ChatGPT stays lazy because its developer mode honours the 401 on the first protected call.
 [2026-09-02] parties children/roles reference parties(id, company_id) with composite FKs, not parties(id): a party UUID from another tenant is rejected by construction instead of relying on each writer to check; ON DELETE SET NULL (party_id) on customers/suppliers because a plain SET NULL would null company_id too (Superagent P2 on #2162)
+[2026-09-02] Edited migration 20260902160000 after merge: its backfill failed on prod (ensure_party: name is required; 3 nameless rows) so it was never applied there, the Supabase main branch sat in MIGRATIONS_FAILED and every later migration was blocked behind it. An unapplied file is not a shipped schema; a follow-up migration could not run before it