feat: Replace nextlove sdk generator with metalsmith codegen

Replace the @seamapi/nextlove-sdk-generator based route generation with
the metalsmith + handlebars + @seamapi/blueprint architecture used by
seamapi/javascript-http. The generated output under seam/routes/ is
byte-identical.

The blueprint drives the route, endpoint, and namespace structure. The
raw OpenAPI spec is still consulted wherever the nextlove generator
derived output from data the blueprint normalizes differently (integer
vs number types, resource schema set and order, parameter flattening);
each of those spots carries a TODO to migrate to the blueprint once
output is allowed to change.

- Add codegen/ with the Metalsmith pipeline, plugin, context builders,
  and Handlebars layouts and partials
- Remove generate-routes.js
- Pin @seamapi/types at 1.910.0 for output parity and use
  @seamapi/blueprint 0.55.0
- Bump del to ^8 to satisfy the @seamapi/smith peer range
- Ignore *.hbs and CODEGEN.md in a new .prettierignore since the
  glimmer parser mangles Python-flavored templates
- Re-include codegen/lib/ in .gitignore (the Python template ignores
  lib/) and ignore the generated CODEGEN.md seed

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_019iX1vWXfXKzUyRJTVm8D7s

Author: claude

.gitignore

@@ -325,3 +325,7 @@ dist
 # yalc
 .yalc/
 yalc.lock
+
+# Codegen
+!codegen/lib/
+CODEGEN.md

.prettierignore

@@ -0,0 +1,4 @@
+# Prettier exceptions
+
+*.hbs
+CODEGEN.md

codegen/layouts/default.hbs

@@ -0,0 +1 @@
+{{contents}}

codegen/layouts/models.hbs

@@ -0,0 +1,17 @@
+from typing import Any, Dict, List, Optional, Union
+from typing_extensions import Self
+import abc
+from dataclasses import dataclass
+from ..utils.deep_attr_dict import DeepAttrDict
+
+{{#each resources}}
+
+{{> model-dataclass}}
+{{/each}}
+{{#each abstractClasses}}
+
+{{> abstract-route-class}}
+{{/each}}
+
+
+{{> abstract-routes}}

codegen/layouts/partials/abstract-route-class.hbs

@@ -0,0 +1,17 @@
+class {{className}}(abc.ABC):
+{{#if showPass}}
+    pass
+{{/if}}
+{{#each childProperties}}
+
+    @property
+    @abc.abstractmethod
+    def {{namespace}}(self) -> {{abstractClassName}}:
+        raise NotImplementedError()
+{{/each}}
+{{#each methods}}
+
+    @abc.abstractmethod
+    def {{name}}(self,{{#if hasParams}} *,{{/if}} {{signatureParams}}) -> {{returnType}}:
+        raise NotImplementedError()
+{{/each}}

codegen/layouts/partials/abstract-routes.hbs

@@ -0,0 +1,5 @@
+@dataclass
+class AbstractRoutes(abc.ABC):
+{{#each routesNamespaces}}
+    {{namespace}}: {{abstractClassName}}
+{{/each}}

codegen/layouts/partials/model-dataclass.hbs

@@ -0,0 +1,13 @@
+@dataclass
+class {{className}}:
+{{#each properties}}
+    {{name}}: {{type}}
+{{/each}}
+
+    @staticmethod
+    def from_dict(d: Dict[str, Any]):
+        return {{className}}(
+{{#each properties}}
+            {{name}}={{#if isDictParam}}DeepAttrDict({{/if}}d.get("{{name}}", None){{#if isDictParam}}){{/if}},
+{{/each}}
+        )

codegen/layouts/partials/route-method.hbs

@@ -0,0 +1,32 @@
+    def {{name}}(self,{{#if hasParams}} *,{{/if}} {{signatureParams}}) -> {{returnType}}:
+        json_payload = {}
+
+{{#each params}}
+        if {{name}} is not None:
+            json_payload["{{name}}"] = {{name}}
+{{/each}}
+
+        {{#unless returnsNone}}res = {{/unless}}self.client.post("{{path}}", json=json_payload)
+{{#if pollsActionAttempt}}
+
+        wait_for_action_attempt = (
+            self.defaults.get("wait_for_action_attempt")
+            if wait_for_action_attempt is None
+            else wait_for_action_attempt
+        )
+
+        return resolve_action_attempt(
+            client=self.client,
+            action_attempt=ActionAttempt.from_dict(res["action_attempt"]),
+            wait_for_action_attempt=wait_for_action_attempt
+        )
+{{else if returnsNone}}
+
+        return None
+{{else if isList}}
+
+        return [{{itemType}}.from_dict(item) for item in {{resAccessor}}]
+{{else}}
+
+        return {{returnType}}.from_dict({{resAccessor}})
+{{/if}}

codegen/layouts/route.hbs

@@ -0,0 +1,30 @@
+from typing import Optional, Any, List, Dict, Union
+from ..client import SeamHttpClient
+from .models import ({{modelImportList}})
+{{#each childClasses}}
+from .{{module}} import {{className}}
+{{else}}
+
+{{/each}}
+{{#if importResolveActionAttempt}}
+from ..modules.action_attempts import resolve_action_attempt
+{{/if}}
+
+
+class {{className}}({{abstractClassName}}):
+    def __init__(self, client: SeamHttpClient, defaults: Dict[str, Any]):
+        self.client = client
+        self.defaults = defaults
+{{#each childClasses}}
+        self._{{namespace}} = {{className}}(client=client, defaults=defaults)
+{{/each}}
+{{#each childClasses}}
+
+    @property
+    def {{namespace}}(self) -> {{className}}:
+        return self._{{namespace}}
+{{/each}}
+{{#each methods}}
+
+{{> route-method}}
+{{/each}}

codegen/layouts/routes-index.hbs

@@ -0,0 +1,13 @@
+from typing import Any, Dict
+from ..client import SeamHttpClient
+from .models import AbstractRoutes
+{{#each namespaces}}
+from .{{namespace}} import {{className}}
+{{/each}}
+
+
+class Routes(AbstractRoutes):
+    def __init__(self, client: SeamHttpClient, defaults: Dict[str, Any]):
+{{#each namespaces}}
+        self.{{namespace}} = {{className}}(client=client, defaults=defaults)
+{{/each}}