fix: make FactoryModule lazy in ConduitClient; supply factoryAddress in all examples

[Fang0067]

Overview

Fixes a crash-on-startup bug where every ConduitClient-based example failed immediately because ConduitClient's constructor unconditionally instantiated FactoryModule, which throws when config.factoryAddress is absent.

Related Issue

Closes #428

Changes

Core SDK

• [MODIFY] src/client.ts
  • Converted factory from an eagerly-initialised readonly field to a lazy getter. FactoryModule is now only constructed on the first access of .factory, so callers that never use factory queries (stream-only consumers, read-only listing via streams.list, etc.) are not forced to supply factoryAddress. Accessing .factory without a factoryAddress still throws FactoryModule's clear, actionable error — but now at the call site rather than in the constructor.

Examples

• [MODIFY] examples/create-stream.ts
  • Reads FACTORY_ADDRESS from env, validates it is set, and passes it to ConduitClient. Updated run-command comment.
• [MODIFY] examples/withdraw.ts
  • Same as above.
• [MODIFY] examples/list-streams.ts
  • Same as above.
• [MODIFY] examples/nextjs-app/lib/conduit.ts
  • Added getFactoryAddress() that reads FACTORY_ADDRESS (server-only env var) and threads it into the ConduitClient config inside getClient().
• [MODIFY] examples/nextjs-app/.env.example
  • Documents the new FACTORY_ADDRESS variable with an explanation of what it is and why it is not NEXT_PUBLIC_-prefixed.

Verification Results

Constructing ConduitClient without factoryAddress no longer throws.
Accessing client.factory without factoryAddress throws FactoryModule's
clear error at the call site (correct behaviour preserved).
All examples now validate FACTORY_ADDRESS at startup and pass it through.

Acceptance Criteria	Status
new ConduitClient({ network: 'testnet', keypair }) does not throw	✅ FactoryModule is now lazy — constructor no longer instantiates it
client.factory without factoryAddress still throws a clear error	✅ FactoryModule's guard is preserved, just deferred to access time
All example scripts run past the new ConduitClient(…) line	✅ All four examples now read and pass FACTORY_ADDRESS from env
examples/nextjs-app getClient() passes factoryAddress	✅ getFactoryAddress() helper added and threaded in
Missing FACTORY_ADDRESS in examples gives a clear error message	✅ Each example exits with an actionable message before constructing the client

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[Jaydbrown]

Thanks for the contribution here — squash-merging this now. Any follow-ups we'll track in a fresh issue. 🚀