[Pather / AutoTool] rework route kwargs into tool_options, and actualyl pass them through AutoTool

MIGRATION.md

@@ -22,13 +22,13 @@ The biggest migration point is that the old routing verbs were renamed:
 | `Pather.pathU(...)` | `Pather.uturn(...)` |
 | `Pather.path_into(...)` | `Pather.trace_into(...)` |
 | `Pather.path_from(src, dst)` | `Pather.at(src).trace_into(dst)` |
-| `RenderPather.path(...)` | `Pather(..., auto_render=False).trace(...)` |
-| `RenderPather.path_to(...)` | `Pather(..., auto_render=False).trace_to(...)` |
-| `RenderPather.mpath(...)` | `Pather(..., auto_render=False).trace(...)` / `Pather(..., auto_render=False).trace_to(...)` |
-| `RenderPather.pathS(...)` | `Pather(..., auto_render=False).jog(...)` |
-| `RenderPather.pathU(...)` | `Pather(..., auto_render=False).uturn(...)` |
-| `RenderPather.path_into(...)` | `Pather(..., auto_render=False).trace_into(...)` |
-| `RenderPather.path_from(src, dst)` | `Pather(..., auto_render=False).at(src).trace_into(dst)` |
+| `RenderPather.path(...)` | `Pather(..., render='deferred').trace(...)` |
+| `RenderPather.path_to(...)` | `Pather(..., render='deferred').trace_to(...)` |
+| `RenderPather.mpath(...)` | `Pather(..., render='deferred').trace(...)` / `Pather(..., render='deferred').trace_to(...)` |
+| `RenderPather.pathS(...)` | `Pather(..., render='deferred').jog(...)` |
+| `RenderPather.pathU(...)` | `Pather(..., render='deferred').uturn(...)` |
+| `RenderPather.path_into(...)` | `Pather(..., render='deferred').trace_into(...)` |
+| `RenderPather.path_from(src, dst)` | `Pather(..., render='deferred').at(src).trace_into(dst)` |
 
 There are also new convenience wrappers:
 
@@ -123,13 +123,13 @@ from masque.builder.renderpather import RenderPather
 from masque.builder import Pather
 
 builder = Pather(...)
-deferred = Pather(..., auto_render=False)
+deferred = Pather(..., render='deferred')
 ```
 
 Top-level imports from `masque` also continue to work.
 
-`Pather` now defaults to `auto_render=True`, so plain construction replaces the
-old `Builder` behavior. Use `Pather(..., auto_render=False)` where you
+`Pather` now defaults to `render='auto'`, so plain construction replaces the
+old `Builder` behavior. Use `Pather(..., render='deferred')` where you
 previously used `RenderPather`.
 
 ## `BasicTool` was replaced
@@ -218,7 +218,7 @@ class MyTool(Tool):
             commit_planner=commit,
             ),)
 
-    def render(self, batch: Sequence[RenderStep], **kwargs: Any):
+    def render(self, batch: Sequence[RenderStep]):
         ...
 ```
 
@@ -281,10 +281,32 @@ class MyTool(Tool):
             commit_planner=commit,
             ),)
 
-    def render(self, batch: Sequence[RenderStep], **kwargs):
+    def render(self, batch: Sequence[RenderStep]):
         ...
 ```
 
+Routing entry points now name every supported route argument explicitly.
+Custom per-route planning values must be placed under `tool_options`:
+
+```python
+pather.jog('A', 4, length=10, tool_options={'process_corner': 'slow'})
+```
+
+The mapping is unpacked only for `Tool.primitive_offers()`. Route arguments do
+not leak into that namespace, and tool options are not forwarded to
+`Tool.render()`. An offer that needs route-specific render behavior must capture
+the selected value in its `commit()` result (`RenderStep.data`). `AutoTool`
+does this automatically for generated straight and S-bend primitives: the flat
+mapping is snapshotted per selected primitive and passed to its generator as
+keyword arguments during rendering. AutoTool options must not change generated
+ports or endpoint geometry. `PathTool` defines no tool options and rejects
+nonempty mappings.
+
+AutoTool does not validate generator keyword signatures during planning. A bad
+keyword therefore raises when the generator runs, normally during rendering.
+Generators that require route options must provide explicit port metadata at
+registration; S-bend generators must also provide an explicit `endpoint`.
+
 Primitive offers are local planning objects:
 
 - `endpoint_at(parameter)` returns the local output `Port`