Add rebalance first slice (3d-7)

First vertical slice for portfolio rebalancing. Domain gains
RebalancePolicy: target-allocation validation (non-empty, per-code
shares positive two-decimal, sum exactly 100); diff computation over
the union of target and held codes (held without target = full exit)
producing BUY amount diffs and SELL unit diffs priced at the current
valuation NAV, clamped to available units, with no orders when a
weight already balances; and the deterministic idempotency key set
(rebalance:{plan}:{date}:{code} plus confirm/redeem counterparts).

Rebalance plans persist as rebalance_plans + rebalance_targets with
rebalance_idempotencies under the shared replay/conflict contract.
ExecuteRebalancePlan snapshots cash plus holdings valued at each
position's latest valuation NAV, then walks the diffs SELL-first
through the same Create/Confirm pipeline used by manual orders,
redemptions and SIP (nothing bypasses confirmation; a held code
without a valuation is skipped with an explicit marker; insufficient
cash/units fail the period visibly instead of silently trimming).

API exposes POST/GET /funds/{id}/rebalance/plans and POST
.../plans/{id}/execute. The frontend adds an 08/REBALANCE panel with
target editing (two codes, sum must equal 100), a plan list with a
manual execute button and post-run outcome rows; executing refreshes
orders/positions so the new orders are immediately visible. Domain
tests cover split validation, diff orders, exit/clamp logic, key
determinism; API tests cover create/execute end-to-end; Web tests
cover decoding and stale-execution protection.

2 files changed, 14 insertions, 1 deletions

diff --git a/src/FundLab.Api/App.fs b/src/FundLab.Api/App.fs
index ac4c174..4ae00de 100644
--- a/src/FundLab.Api/App.fs
+++ b/src/FundLab.Api/App.fs
@@ -544,7 +544,12 @@ module App =
                                 | Some code, Some percentText ->
                                     match tryDecimal "targetPercent" percentText with
                                     | Ok percent ->
-                                        let targetRow: RebalancePolicy.TargetAllocation = { InstrumentCode = code; TargetPercent = percent }
+                                        let targetRow: RebalancePolicy.TargetAllocation =
+                                            {
+                                                RebalancePolicy.TargetAllocation.InstrumentCode = code
+                                                TargetPercent = percent
+                                            }
+
                                         rows.Add(targetRow)
                                     | Error message -> failure <- Some message
                                 | _ -> failure <- Some "each target needs instrumentCode and targetPercent"
diff --git a/src/FundLab.Api/Persistence.fs b/src/FundLab.Api/Persistence.fs
index d64fe98..6c0374a 100644
--- a/src/FundLab.Api/Persistence.fs
+++ b/src/FundLab.Api/Persistence.fs
@@ -612,6 +612,14 @@ type FundRepository(connectionString: string) =
             created_at timestamptz NOT NULL DEFAULT now()
         );
 
+        CREATE TABLE IF NOT EXISTS rebalance_idempotencies (
+            idempotency_key text PRIMARY KEY,
+            request_hash text NOT NULL,
+            plan_id uuid NOT NULL REFERENCES rebalance_plans(id),
+            fund_id uuid NOT NULL REFERENCES funds(id),
+            created_at timestamptz NOT NULL DEFAULT now()
+        );
+
         CREATE TABLE IF NOT EXISTS rebalance_targets (
             plan_id uuid NOT NULL REFERENCES rebalance_plans(id),
             instrument_code text NOT NULL REFERENCES instruments(code),