Add cost basis source tracking with manual override and lock protection (#623)

* Add cost basis tracking and management to holdings

- Added migration to introduce `cost_basis_source` and `cost_basis_locked` fields to `holdings`.
- Implemented backfill for existing holdings to set `cost_basis_source` based on heuristics.
- Introduced `Holding::CostBasisReconciler` to manage cost basis resolution logic.
- Added user interface components for editing and locking cost basis in holdings.
- Updated `materializer` to integrate reconciliation logic and respect locked holdings.
- Extended tests for cost basis-related workflows to ensure accuracy and reliability.

* Fix cost basis calculation in holdings controller

- Ensure `cost_basis` is converted to decimal for accurate arithmetic.
- Fix conditional check to properly validate positive `cost_basis`.

* Improve cost basis validation and error handling in holdings controller

- Allow zero as a valid cost basis for gifted/inherited shares.
- Add error handling with user feedback for invalid cost basis values.

---------

Co-authored-by: Josh Waldrep <joshua.waldrep5+github@gmail.com>

app/javascript/controllers/cost_basis_form_controller.js

@@ -0,0 +1,30 @@
+import { Controller } from "@hotwired/stimulus"
+
+// Handles bidirectional conversion between total cost basis and per-share cost
+// in the manual cost basis entry form.
+export default class extends Controller {
+  static targets = ["total", "perShare", "perShareValue"]
+  static values = { qty: Number }
+
+  // Called when user types in the total cost basis field
+  // Updates the per-share display and input to show the calculated value
+  updatePerShare() {
+    const total = Number.parseFloat(this.totalTarget.value) || 0
+    const qty = this.qtyValue || 1
+    const perShare = qty > 0 ? (total / qty).toFixed(2) : "0.00"
+    this.perShareValueTarget.textContent = perShare
+    if (this.hasPerShareTarget) {
+      this.perShareTarget.value = perShare
+    }
+  }
+
+  // Called when user types in the per-share field
+  // Updates the total cost basis field with the calculated value
+  updateTotal() {
+    const perShare = Number.parseFloat(this.perShareTarget.value) || 0
+    const qty = this.qtyValue || 1
+    const total = (perShare * qty).toFixed(2)
+    this.totalTarget.value = total
+    this.perShareValueTarget.textContent = perShare.toFixed(2)
+  }
+}

app/javascript/controllers/drawer_cost_basis_controller.js

@@ -0,0 +1,33 @@
+import { Controller } from "@hotwired/stimulus"
+
+// Handles the inline cost basis editor in the holding drawer.
+// Shows/hides the form and handles bidirectional total <-> per-share conversion.
+export default class extends Controller {
+  static targets = ["form", "total", "perShare", "perShareValue"]
+  static values = { qty: Number }
+
+  toggle(event) {
+    event.preventDefault()
+    this.formTarget.classList.toggle("hidden")
+  }
+
+  // Called when user types in total cost basis field
+  updatePerShare() {
+    const total = Number.parseFloat(this.totalTarget.value) || 0
+    const qty = this.qtyValue || 1
+    const perShare = qty > 0 ? (total / qty).toFixed(2) : "0.00"
+    this.perShareValueTarget.textContent = perShare
+    if (this.hasPerShareTarget) {
+      this.perShareTarget.value = perShare
+    }
+  }
+
+  // Called when user types in per-share field
+  updateTotal() {
+    const perShare = Number.parseFloat(this.perShareTarget.value) || 0
+    const qty = this.qtyValue || 1
+    const total = (perShare * qty).toFixed(2)
+    this.totalTarget.value = total
+    this.perShareValueTarget.textContent = perShare.toFixed(2)
+  }
+}