Fixes all 16 cargo check warnings across the codebase:

**Cargo.toml fixes:**
- Remove invalid `doc = false` key from git dependency

**Dead code warnings:**
- Add #[allow(dead_code)] to reference implementations and test utilities
- PoI struct and helper functions (proof_of_indexing/reference.rs)
- AscSubgraphEntityOp enum (runtime/wasm)
- CopyVid struct (store/postgres)

**Lifetime syntax warnings:**
- Add explicit '_ lifetime parameters to fix confusing syntax
- Fix 11 lifetime warnings across store, runtime, and utility modules

All tests pass and cargo check now produces zero warnings.

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-authored-by: Claude <noreply@anthropic.com>

In particular, include the deployment hash

The current code in `SubgraphAssignmentProvider.start` fetched the manifest
from IPFS before starting a subgraph. But the code calling `start`,
ultimately `SubgraphRegistrar.start_assigned_subgraphs` waited for all
subgraphs to start successfully before processing assignment events.

That could lead to a situation where a slow IPFS server, even if it was
slow for just one subgraph, could keep a node from processing assignment
events.

With these changes, interacting with IPFS is deferred to the future that is
spawned for running the subgraph so that slow IPFS can slow how long it
takes for a subgraph to start, but not the system overall.