feat(PBI-76): user-settings DB-store infrastructure (Phase 0) (#185)

* docs(PBI-76): plan for user-settings DB-store

Persists view/filter prefs in User.settings (Json) instead of
localStorage. SSR-correct hydration, cross-tab sync via
LISTEN/NOTIFY + SSE, cross-device persistence.

Phased: 0=infra, 1=migrate flicker sources, 2=cookie consolidation.

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

* feat(PBI-76): User.settings json column + migration

Adds JSONB column to users table for persistent user prefs.
Idempotent SQL — safe on databases where column already exists.

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

* feat(PBI-76): user-settings types and merge helpers

Zod schema for User.settings shape (views/devTools), deep-merge
helper that replaces arrays and merges nested objects, and a
safe parser that returns defaults on invalid input.

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

* feat(PBI-76): updateUserSettingsAction with notify

Validates patch via Zod, deep-merges with current settings in
a transaction, persists to DB, and emits pg_notify on
scrum4me_changes for cross-tab/cross-device sync. Demo accounts
get 403, unauthenticated 401, invalid input 422.

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

* feat(PBI-76): user-settings zustand store with optimistic flow

Hydrate from prop (SSR-correct), setPref via path with optimistic
update + rollback on server error, applyServerPatch for SSE-driven
cross-tab updates. Demo accounts skip server-write entirely.

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

* feat(PBI-76): SSE route for user-settings

User-scoped /api/realtime/user-settings stream that filters
scrum4me_changes notifications on kind=user_settings and matching
userId. Forwards the patch as a data: event so other tabs can
applyServerPatch without re-fetching settings.

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

* feat(PBI-76): user-settings bridge mounted in app layout

Hydrates the zustand store with the user's persisted settings via
prop (SSR-correct, no flicker). Opens an EventSource to
/api/realtime/user-settings so changes from other tabs/devices
flow into the same store. Demo accounts skip the SSE subscription.

Layout now selects user.settings alongside the other user fields,
no extra DB roundtrip.

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

* test(PBI-76): user-settings lib/action/store coverage

22 vitest cases covering merge semantics (no mutation, array
replace, nested merge), Zod schema strictness, server action
auth/demo/validation paths, and the optimistic store flow
including rollback and demo-mode skip.

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

* chore(PBI-76): sync package-lock to v1.3.3

Lockfile drifted after @prisma/client reinstall during the
schema regenerate. No dependency changes — just the version
field tracking package.json bumped in #184.

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

---------

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

prisma/schema.prisma

@@ -147,6 +147,7 @@ model User {
   active_product      Product?         @relation("UserActiveProduct", fields: [active_product_id], references: [id], onDelete: SetNull)
   idea_code_counter   Int              @default(0)
   min_quota_pct       Int              @default(20)
+  settings            Json             @default("{}")
   created_at          DateTime         @default(now())
   updated_at          DateTime         @updatedAt
   roles               UserRole[]