feat(proxy): client restriction refactor - blockedClients + Claude Code sub-client detection

drizzle/0074_wide_retro_girl.sql

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+ALTER TABLE "providers" ADD COLUMN "allowed_clients" jsonb DEFAULT '[]'::jsonb NOT NULL;--> statement-breakpoint
+ALTER TABLE "providers" ADD COLUMN "blocked_clients" jsonb DEFAULT '[]'::jsonb NOT NULL;--> statement-breakpoint
+ALTER TABLE "users" ADD COLUMN "blocked_clients" jsonb DEFAULT '[]'::jsonb NOT NULL;

drizzle/0075_faithful_speed_demon.sql

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+DROP INDEX IF EXISTS "idx_usage_ledger_key_cost";--> statement-breakpoint
+CREATE INDEX IF NOT EXISTS "idx_message_request_session_user_info" ON "message_request" USING btree ("session_id","created_at","user_id","key") WHERE "message_request"."deleted_at" IS NULL;--> statement-breakpoint
+CREATE INDEX IF NOT EXISTS "idx_usage_ledger_user_cost_cover" ON "usage_ledger" USING btree ("user_id","created_at","cost_usd") WHERE "usage_ledger"."blocked_by" IS NULL;--> statement-breakpoint
+CREATE INDEX IF NOT EXISTS "idx_usage_ledger_provider_cost_cover" ON "usage_ledger" USING btree ("final_provider_id","created_at","cost_usd") WHERE "usage_ledger"."blocked_by" IS NULL;--> statement-breakpoint
+CREATE INDEX IF NOT EXISTS "idx_usage_ledger_key_cost" ON "usage_ledger" USING btree ("key","created_at","cost_usd") WHERE "usage_ledger"."blocked_by" IS NULL;