Flip every user-facing read (dashboard, cashflow, transactions, budgets,
accounts, settings, analytics, sync, shared props) from user-scoped to
active-space-scoped via explicit $space->… relations, and re-key the category
tree, spending, and budget-assignment services by space_id. Authorization moves
from creator-ownership to space membership.
Add the visible spaces layer behind a Pennant 'spaces' flag: a sidebar space
switcher, a settings page to create/rename/delete/switch spaces, per-space
offline-cache flushing, and the currentSpace/spaces shared props. Data creation
is unchanged — the BelongsToSpace trait already stamps space_id from the active
space. Isolation tests prove no cross-space leakage.
## Spaces / Business plan — Phase 0: invisible foundation
First of **three stacked PRs** introducing multi-tenant **Spaces** (the
basis for the Business plan). This one is a **pure, behaviour-preserving
foundation**: it can ship to production on its own with zero
user-visible change.
- **Stacked PRs:** this → `enterprise-spaces-ui` (Phase 1+2) →
`enterprise-spaces-invitations` (Phase 3).
### What a Space is
A Space groups its own accounts, connections, transactions, categories,
labels, budgets and rules. **Every user gets one invisible "Personal"
space**, provisioned automatically on creation — so the architecture is
identical for free, Standard and Business accounts, even though only
Business will ever see more than one.
### What this PR does (no behaviour change)
- `spaces`, `space_user`, `space_invitations` tables;
`users.current_space_id`; a nullable, indexed `space_id` on the 8 owned
tables (plain column, **no FK** — avoids a validating table-scan/lock on
`transactions` during a phased rollout).
- `Space` model + `BelongsToSpace` trait that stamps `space_id` on
create (from the row's user's current space; a transaction inherits its
account's space, so bank-sync lands rows correctly).
- Idempotent, chunked `spaces:backfill` command (run from a migration)
that gives every existing user a personal space and stamps their rows —
so the read switch in the next PR is safe.
- **Reads are untouched here** (still user-scoped); every user has
exactly one space, so behaviour is identical.
### Testing
- New `tests/Feature/Spaces/SpaceFoundationTest.php` (provisioning,
default-space stamping, account-anchored transaction space,
stale-pointer self-heal, backfill).
- Full suite green.
### Notes / deliberate simplifications
- `space_id` stays **nullable** (populated by backfill + on every
write); the NOT NULL constraint is deferred until prod is confirmed
fully backfilled.
- For very large `transactions` tables, `spaces:backfill` can be run
out-of-band before deploy so the migration's call is a no-op.
Víctor Falcón