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---

docs/pipeline/index.md

@@ -6,7 +6,7 @@ are the single source of truth for the workflow files.
 ## CI pipeline
 
 The CI pipeline runs on every push and pull request to `main`. It is defined
-by [`pipelines/ci.yaml`](https://github.com/acdl/acdl/blob/main/pipelines/ci.yaml),
+by [`pipelines/ci.yml`](https://github.com/acdl/acdl/blob/main/pipelines/ci.yml),
 validated against
 [`schemas/pipeline.schema.json`](https://github.com/acdl/acdl/blob/main/schemas/pipeline.schema.json).
 Both platform-runner workflow files implement the same contract and are
@@ -31,7 +31,7 @@ bash scripts/run_ci.sh --quiet    # suppress per-stage banners
 ## Deployment pipeline
 
 The deployment pipeline runs when a consumer submits a contract. It is
-defined by [`pipelines/deploy.yaml`](https://github.com/acdl/acdl/blob/main/pipelines/deploy.yaml),
+defined by [`pipelines/contract.yml`](https://github.com/acdl/acdl/blob/main/pipelines/contract.yml),
 validated against
 [`schemas/deploy-pipeline.schema.json`](https://github.com/acdl/acdl/blob/main/schemas/deploy-pipeline.schema.json).
 It is exposed to consumer repos as a **reusable workflow**: