feat: add descriptive help text to graph designer properties

Add inline descriptions to workflow settings, orchestration mode,
edge inspector, node inspectors, and condition editor properties
so users understand what each option does at a glance.

- Execution Mode: explains off-thread vs lockstep behavior
- Max Iterations: clarifies it prevents runaway loops
- State Scopes: describes shared state containers
- Edge Kind: explains direct, fan-out, fan-in semantics
- Loop Edge: describes iterative cycle behavior
- Reasoning: explains effort vs answer quality tradeoff
- Triage Agent, Tool-Call Filtering, Max Rounds, etc.
- Result Variable, Require Approval, Port ID, Condition

Also enhances FormField component with optional description prop.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

src/renderer/components/WorkflowEditor.tsx

@@ -691,6 +691,9 @@ function WorkflowSettingsPanel({
             <option value="off-thread">Off-thread</option>
             <option value="lockstep">Lockstep</option>
           </select>
+          <p className="text-[11px] leading-relaxed text-[var(--color-text-muted)]">
+            Off-thread executes in the background without blocking. Lockstep waits for each step to finish before proceeding.
+          </p>
         </label>
 
         <label className="block space-y-1.5">
@@ -712,6 +715,9 @@ function WorkflowSettingsPanel({
             type="number"
             value={workflow.settings.maxIterations ?? ''}
           />
+          <p className="text-[11px] leading-relaxed text-[var(--color-text-muted)]">
+            Safety limit on total step executions to prevent runaway loops.
+          </p>
         </label>
 
         <div className="col-span-2 flex items-center justify-between rounded-lg border border-[var(--color-border)] bg-[var(--color-surface-1)] px-4 py-3">
@@ -790,9 +796,14 @@ function WorkflowSettingsPanel({
         {/* State Scopes */}
         <div className="col-span-2 space-y-3">
           <div className="flex items-center justify-between">
-            <span className="text-[12px] font-semibold uppercase tracking-wider text-[var(--color-text-muted)]">
-              State Scopes
-            </span>
+            <div>
+              <span className="text-[12px] font-semibold uppercase tracking-wider text-[var(--color-text-muted)]">
+                State Scopes
+              </span>
+              <p className="mt-0.5 text-[11px] leading-relaxed text-[var(--color-text-muted)]">
+                Named containers for shared state that persists across workflow steps.
+              </p>
+            </div>
             <button
               className="flex size-6 items-center justify-center rounded-md text-[var(--color-text-muted)] transition-all duration-200 hover:bg-[var(--color-accent)]/10 hover:text-[var(--color-accent)]"
               onClick={() => {