refactor(P57): contract surface redesign + rename + .yml repo-wide

Contract surface redesign:
- New top-level fields: id (3-6 char acronym → stack.name), name (full → stack.title),
  infrastructure (map keyed by module name, replaces module:)
- Drop uses: field (dead reference; version pin lives in CI workflow uses: line)
- Drop top-level module/inputs (now nested under infrastructure map)
- Per-module optional version (defaults to latest published from registry)
- Multi-module contracts: one file deploys N modules in one pipeline run,
  resource IDs namespaced with module name to avoid collisions
- stack.schema.json: add optional title field for display name

Rename:
- pipelines/deploy.yaml → pipelines/contract.yml (declarative spec, not a pipeline)
- pipelines/ci.yaml → pipelines/ci.yml
- All 44 .yaml files → .yml repo-wide (contracts, module examples, kyverno policies)
- .acdl/contract.yaml → .acdl/contract.yml

Resolver (core/contract_resolver.py):
- Rewrite resolve() to loop infrastructure map, default version to latest,
  merge module fragments into one stack with namespaced resource IDs
- _latest_version() picks highest non-deprecated from registry
- _namespace_resources() prefixes IDs + rewrites ref: expressions for multi-module
- Single-module path: unprefixed IDs (backward compatible)

Verification:
- 494 tests pass (0 contract-shape failures)
- Local E2E passes (contract → resolver → adapter → local ECS HTTP 200 → outbox)

---ci---
project: acdl
phase: 57
milestone: v1.10.2
status: execute
---/ci---

schemas/stack.schema.json

@@ -20,7 +20,11 @@
         "name": {
           "type": "string",
           "pattern": "^[a-z][a-z0-9-]*$",
-          "description": "Stack name matching the module folder name."
+          "description": "Operational stack identity (short acronym from the contract id). Used for the Terraform state key (spike/<name>/terraform.tfstate), the ECS service name, and the outbox event identity."
+        },
+        "title": {
+          "type": "string",
+          "description": "Human-readable stack name (from the contract name). Used for display in PR comments, evidence records, and leadership dashboards. Optional; omitted when the contract does not provide a name."
         },
         "kind": {
           "type": "string",