Rework balances around per-parent days left and deduce the partner from FK

Manual entry now takes one parent's sjukpenningnivå, lägstanivå and
dubbeldagar left (plus optional reserved days) and derives the rest in
build_snapshot, shared with the scraper. The scraper also reads the
family panel and exposes a partner deduction; with two parents it is
saved as a 'deduced' snapshot (migration 002). Parent count is the single
source of entitlement: one member gets 480 days and 96 savable at age 4,
two get 240 and 48 each. Workspaces are capped at two parents.

Also lands the in-flight squash of migrations 002–011 into the initial
schema and the removal of planning_mode.

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

backend/app/db/connection.py

@@ -25,8 +25,6 @@ _FULL_SCHEMA = """
 CREATE TABLE IF NOT EXISTS workspace (
     id TEXT PRIMARY KEY,
     name TEXT NOT NULL,
-    planning_mode TEXT NOT NULL DEFAULT 'solo'
-        CHECK (planning_mode IN ('solo','couple')),
     created_at TIMESTAMP NOT NULL
 );
 
@@ -107,6 +105,7 @@ CREATE TABLE IF NOT EXISTS leave_wish (
     parent_personal_data_uuid TEXT,
     window_mode TEXT NOT NULL DEFAULT 'fixed'
         CHECK (window_mode IN ('fixed','flexible')),
+    wants_dubbeldag INTEGER NOT NULL DEFAULT 0,
     created_at TIMESTAMP NOT NULL,
     updated_at TIMESTAMP NOT NULL,
     FOREIGN KEY (workspace_id) REFERENCES workspace(id) ON DELETE CASCADE,
@@ -119,7 +118,7 @@ CREATE TABLE IF NOT EXISTS parental_leave_fetch (
     personal_data_uuid TEXT NOT NULL,
     workspace_id TEXT NOT NULL,
     child_id TEXT NOT NULL,
-    source TEXT NOT NULL CHECK (source IN ('scraped','manual')),
+    source TEXT NOT NULL CHECK (source IN ('scraped','manual','deduced')),
     fetched_at TIMESTAMP NOT NULL,
     total_days INTEGER NOT NULL,
     days_used INTEGER NOT NULL,
@@ -191,8 +190,8 @@ CREATE TABLE IF NOT EXISTS tip_dismissal (
     FOREIGN KEY (workspace_id) REFERENCES workspace(id) ON DELETE CASCADE
 );
 
--- Indexes (migration 011). Mirrored verbatim (same columns, same order, no
--- partial indexes) from migrations/versions/011_add_indexes.py so
+-- Indexes. Kept in step (same columns, same order, no partial indexes) with
+-- migrations/versions/001_initial_schema.py so
 -- tests/integration/test_schema_parity.py, which compares index sets between
 -- the Alembic chain and this hand-maintained DDL, stays green. See the
 -- backend-perf audit §4 for what each index serves.