feat: read-only FHIR R4 server (share records over /fhir)

Expose temetro's own records as a read-only FHIR R4 server at /fhir,
authenticated with per-clinic API keys (tmf_… bearer tokens, SHA-256
hashed, shown once). Serves Patient, Observation (labs + vitals),
AllergyIntolerance, Condition, MedicationRequest, Encounter and
Appointment as text-only CodeableConcepts (temetro stores free-text
clinical values); CapabilityStatement at /fhir/metadata (unauth).
Searchset Bundles with _count/_offset pagination and self/next/prev
links; every request is org-scoped and written to the activity log.
Keys are created/revoked under Settings → Integrations (owner/admin).

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

backend/drizzle/0031_stiff_gateway.sql

@@ -0,0 +1,15 @@
+CREATE TABLE "fhir_api_keys" (
+	"id" uuid PRIMARY KEY DEFAULT gen_random_uuid() NOT NULL,
+	"organization_id" text NOT NULL,
+	"name" text NOT NULL,
+	"key_hash" text NOT NULL,
+	"created_by" text,
+	"created_at" timestamp DEFAULT now() NOT NULL,
+	"last_used_at" timestamp,
+	"revoked_at" timestamp,
+	CONSTRAINT "fhir_api_keys_key_hash_unique" UNIQUE("key_hash")
+);
+--> statement-breakpoint
+ALTER TABLE "fhir_api_keys" ADD CONSTRAINT "fhir_api_keys_organization_id_organization_id_fk" FOREIGN KEY ("organization_id") REFERENCES "public"."organization"("id") ON DELETE cascade ON UPDATE no action;--> statement-breakpoint
+ALTER TABLE "fhir_api_keys" ADD CONSTRAINT "fhir_api_keys_created_by_user_id_fk" FOREIGN KEY ("created_by") REFERENCES "public"."user"("id") ON DELETE set null ON UPDATE no action;--> statement-breakpoint
+CREATE INDEX "fhir_api_keys_org_idx" ON "fhir_api_keys" USING btree ("organization_id");

backend/drizzle/meta/_journal.json

@@ -218,6 +218,13 @@
       "when": 1783093188246,
       "tag": "0030_medical_blur",
       "breakpoints": true
+    },
+    {
+      "idx": 31,
+      "version": "7",
+      "when": 1783117115021,
+      "tag": "0031_stiff_gateway",
+      "breakpoints": true
     }
   ]
 }