feat: TTL enforcement and operational hardening (SAND-WP-0009)

Add TTL parser, expires_at on create, extend_ttl and expire/reap APIs,
activity-core integration doc, repo classification, registry refresh,
HTTP parity, and 69 tests.

.repo-classification.yaml

@@ -0,0 +1,25 @@
+repo_classification:
+  standard: Repo Classification Standard
+  version: '1.0'
+  classified_at: '2026-06-24'
+  classified_by: codex
+  category: tooling
+  domain: infotech
+  secondary_domains:
+  - agents
+  capability_tags:
+  - sandbox
+  - isolation
+  - provision
+  - execution
+  - orchestration
+  business_stake:
+  - technology
+  - execution
+  - automation
+  business_mechanics:
+  - operation
+  - coordination
+  notes: >
+    Sandbox establishment meta-framework — profiles, extensions, routing,
+    lifecycle, TTL, and host telemetry for agentic and deterministic workloads.