fix(P08 prep): rename platform/ -> acdl_platform/ (stdlib shadow fix)

---ci---
project: acdl
phase: 8
milestone: v1.1
status: plan-as-execute
persona: lead-developer
task: T-8.0
type: prerequisite-fix
---/ci---

The Phase 07 P1 ('platform/ package shadows stdlib platform module')
became a Phase 08 blocker: boto3 imports uuid -> platform.system(),
which fails when the repo's platform/ package is on sys.path[0]. Renamed
platform/ -> acdl_platform/ (the verifier's recommended v1.2 fix, pulled
forward because Phase 08 needs boto3).

- git mv platform/ acdl_platform/ (history preserved)
- verify_phase07.sh: updated paths; removed the /tmp workaround (no
  longer needed; the shadow is gone)
- verify_phase06.sh: updated the new-dirs check for the rename
- README.md: layout table updated

Both verify_phase06.sh and verify_phase07.sh still pass; confidence_signal
now imports + runs correctly from the repo root. boto3 imports clean.

README.md

@@ -28,7 +28,7 @@ a configuration file, or a Terraform module.
 
 | Path | Purpose | Populated |
 |------|---------|-----------|
-| `platform/` | Platform code: confidence signal, contract resolver, outbox, HITL/ledger designs | Phase 07+ |
+| `acdl_platform/` | Platform code: confidence signal, contract resolver, outbox, HITL/ledger designs (renamed from `platform/` in Phase 08 to avoid shadowing the stdlib `platform` module) | Phase 07+ |
 | `schemas/` | JSON Schemas: IR, PolicyCheckResult, contract | Phase 07 |
 | `adapters/` | Substrate adapters (Terraform adapter in v1; the only substrate-specific code per §12) | Phase 09 |
 | `terraform/` | State backend + provider config (S3 state + DynamoDB lock) | Phase 08+ |