feat(bot): add shared topic router

infra/terraform/README.md

@@ -72,9 +72,9 @@ Recommended approach:
 - Use `terraform.tfvars` per environment (`dev.tfvars`, `prod.tfvars`)
 - Keep `project_id` separate for dev/prod when possible
 - Keep non-secret bot config in `*.tfvars`:
-  - optional `bot_parser_model`
   - optional `bot_purchase_parser_model`
   - optional `bot_assistant_model`
+  - optional `bot_assistant_router_model`
   - optional assistant runtime knobs:
     `bot_assistant_timeout_ms`,
     `bot_assistant_memory_max_turns`,

infra/terraform/main.tf

@@ -90,15 +90,15 @@ module "bot_api_service" {
     {
       NODE_ENV = var.environment
     },
-    var.bot_parser_model == null ? {} : {
-      PARSER_MODEL = var.bot_parser_model
-    },
     var.bot_purchase_parser_model == null ? {} : {
       PURCHASE_PARSER_MODEL = var.bot_purchase_parser_model
     },
     var.bot_assistant_model == null ? {} : {
       ASSISTANT_MODEL = var.bot_assistant_model
     },
+    var.bot_assistant_router_model == null ? {} : {
+      ASSISTANT_ROUTER_MODEL = var.bot_assistant_router_model
+    },
     var.bot_assistant_timeout_ms == null ? {} : {
       ASSISTANT_TIMEOUT_MS = tostring(var.bot_assistant_timeout_ms)
     },

infra/terraform/terraform.tfvars.example

@@ -11,9 +11,9 @@ mini_app_image  = "europe-west1-docker.pkg.dev/my-gcp-project/household-bot/mini
 database_url_secret_id   = "database-url"
 telegram_bot_token_secret_id = "telegram-bot-token"
 openai_api_key_secret_id = "openai-api-key"
-bot_parser_model             = "gpt-4o-mini"
 bot_purchase_parser_model    = "gpt-4o-mini"
 bot_assistant_model          = "gpt-4o-mini"
+bot_assistant_router_model   = "gpt-5-nano"
 bot_assistant_timeout_ms     = 20000
 bot_assistant_memory_max_turns = 12
 bot_assistant_rate_limit_burst = 5

infra/terraform/variables.tf

@@ -69,13 +69,6 @@ variable "telegram_bot_token_secret_id" {
   default     = "telegram-bot-token"
 }
 
-variable "bot_parser_model" {
-  description = "Optional PARSER_MODEL override for bot runtime"
-  type        = string
-  default     = null
-  nullable    = true
-}
-
 variable "bot_purchase_parser_model" {
   description = "Optional PURCHASE_PARSER_MODEL override for bot runtime"
   type        = string
@@ -90,6 +83,13 @@ variable "bot_assistant_model" {
   nullable    = true
 }
 
+variable "bot_assistant_router_model" {
+  description = "Optional ASSISTANT_ROUTER_MODEL override for bot runtime"
+  type        = string
+  default     = null
+  nullable    = true
+}
+
 variable "bot_assistant_timeout_ms" {
   description = "Optional ASSISTANT_TIMEOUT_MS override for bot runtime"
   type        = number