feat: allow orphaned deployments to be queried

[tmigone]

Changes

This PR adds support for querying orphaned deployments, deployments that have active indexer allocations but are not linked to any active subgraph (activeSubgraphCount: 0). Previously, the gateway discovered deployments exclusively through active subgraphs. This meant orphaned deployments were invisible to the gateway and returned error even when indexers were actively indexing and serving them.

A few notes on the implementation:

• The network subgraph query is extended with a parallel orphanedDeployments subquery that fetches deployments where activeSubgraphCount: 0 and allocations have status: Active.
• Both subqueries use independent pagination cursors and run together until both complete.
• Results are merged into the network snapshot during pre-processing, with subgraph-linked deployments taking precedence over orphaned ones.
• Restricted API keys cannot query orphaned deployments as the enforcement happens at the subgraph level.