feat(councils): add scaffold prompt hooks and checked-in scaffold files

src/config/schema.ts

@@ -863,6 +863,8 @@ const agentConfigsSchema = z.record(z.string(), agentConfigEntrySchema).default(
 const councilsGroupConfigSchema = z.object({
   arbiter_agent: z.string().min(1),
   freethinker_agent: z.string().min(1),
+  grounder_agent: z.string().min(1).optional(),
+  writer_agent: z.string().min(1).optional(),
   group_prompt_prefix: z.string().min(1),
   novelty_bias: z.enum(['low', 'medium', 'high']).default('medium'),
   risk_tolerance: z.enum(['low', 'medium', 'high']).default('medium'),
@@ -883,6 +885,7 @@ const councilsSchema = z.object({
   }).default({}),
   strict_grounding: z.boolean().default(false),
   strict_meta_validation: z.boolean().default(true),
+  scaffold_path: z.string().optional(),
   groups: z.object({
     D: councilsGroupConfigSchema.default({
       arbiter_agent: 'council_d_arbiter',
@@ -910,6 +913,7 @@ const councilsSchema = z.object({
     }),
   }).default({}),
   meta_arbiter_agent: z.string().min(1).default('council_meta_arbiter'),
+  meta_writer_agent: z.string().min(1).optional(),
 }).default({});
 
 const routingSchema = z.object({