fix: correct stale min attribute and MCP wording from inventory removal

Three small leftovers from Task 7 / the inventory-quantity-tracking
removal that a final review caught:

- Edit.razor's custom-stock quantity input still had min="1" even
  though its own helper text says "Use -1 for unlimited", validation
  already accepts -1, and the add-form defaults Quantity to -1 - so
  the field rendered pre-populated with a value the browser's native
  min validation flagged as invalid. Matches the min="-1" fix already
  applied to the catalog-stock input in Task 7.
- optimize_job's MCP tool description still claimed the optimizer
  falls back to "available inventory" when no stock is configured -
  that auto-discovery fallback was removed in Task 3. An LLM reads
  this description as ground truth, so stale wording here actively
  misleads tool use. Also tightened add_job_stock's stockItemId/
  isCustomLength wording, which still said "inventory" for what is
  now just the stock catalog.
- CLAUDE.md's CutListPackingService summary said InStockBins comes
  "from inventory", nudging future readers back toward the
  auto-discovery mental model this plan removed.

CutList.Mcp/JobTools.cs

@@ -257,9 +257,9 @@ public class JobTools
         string length,
         [Description("Quantity available (-1 for unlimited, default -1)")]
         int quantity = -1,
-        [Description("Stock item ID from inventory (optional - links to tracked inventory)")]
+        [Description("Stock item ID from the stock catalog (optional - links to a specific catalog stock item)")]
         int? stockItemId = null,
-        [Description("True if this is a custom length not from inventory (default false)")]
+        [Description("True if this is a custom length not sourced from the stock catalog (default false)")]
         bool isCustomLength = false,
         [Description("Priority - lower number = used first (default 10)")]
         int priority = 10)
@@ -304,7 +304,7 @@ public class JobTools
 
     #region Optimization
 
-    [McpServerTool(Name = "optimize_job"), Description("Runs bin packing optimization on a job. The job must have parts defined. If stock is defined, it will be used; otherwise the optimizer uses available inventory. Returns optimized cut layouts per material with efficiency stats.")]
+    [McpServerTool(Name = "optimize_job"), Description("Runs bin packing optimization on a job. The job must have parts defined, and stock must be explicitly configured on the job (via add_job_stock) for each material used by its parts - there is no fallback to inventory; parts with no matching stock configured come back as items not placed. Returns optimized cut layouts per material with efficiency stats.")]
     public async Task<OptimizeJobResult> OptimizeJob(
         [Description("Job ID")]
         int jobId,