feat(routing): add routing_rules schema, condition types, and action types (M4-001/002/003)

- Add routing_rules table to packages/db with scope, priority, conditions (jsonb), and action (jsonb) columns; generate migration 0004
- Define RoutingCondition, RoutingAction, RoutingRule, TaskClassification, and RoutingDecision types in apps/gateway/src/agent/routing/routing.types.ts
- Expand @mosaic/types routing/index.ts to export all M4 types (TaskType, Complexity, Domain, CostTier+local, Capability) alongside existing RoutingCriteria/RoutingResult
- Fix pre-existing type errors in routing.service.ts (local CostTier) and default-rules.ts (count optional chaining, unknown cast)
- Fix pre-existing Prettier violations in agent module and provider files

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

packages/db/drizzle/0004_bumpy_miracleman.sql

@@ -0,0 +1,17 @@
+CREATE TABLE "routing_rules" (
+	"id" uuid PRIMARY KEY DEFAULT gen_random_uuid() NOT NULL,
+	"name" text NOT NULL,
+	"priority" integer NOT NULL,
+	"scope" text DEFAULT 'system' NOT NULL,
+	"user_id" text,
+	"conditions" jsonb NOT NULL,
+	"action" jsonb NOT NULL,
+	"enabled" boolean DEFAULT true NOT NULL,
+	"created_at" timestamp with time zone DEFAULT now() NOT NULL,
+	"updated_at" timestamp with time zone DEFAULT now() NOT NULL
+);
+--> statement-breakpoint
+ALTER TABLE "routing_rules" ADD CONSTRAINT "routing_rules_user_id_users_id_fk" FOREIGN KEY ("user_id") REFERENCES "public"."users"("id") ON DELETE cascade ON UPDATE no action;--> statement-breakpoint
+CREATE INDEX "routing_rules_scope_priority_idx" ON "routing_rules" USING btree ("scope","priority");--> statement-breakpoint
+CREATE INDEX "routing_rules_user_id_idx" ON "routing_rules" USING btree ("user_id");--> statement-breakpoint
+CREATE INDEX "routing_rules_enabled_idx" ON "routing_rules" USING btree ("enabled");