Require existing SENDx and persist in deployments

[youngkidwarrior]

Why:
Ensure deployments include SENDx and pass it into manager for
consistent wiring.

Test plan:

• Run deploy script on anvil.
• Check deployments JSON includes sendx.

[youngkidwarrior]

Warning

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• Require existing SENDx and persist in deployments #16 👈 (View in Graphite)
• Accept existing SuperToken in RewardsManager ctor #15 : 1 other dependent PR (#18 )
• Add RewardsManager for pool units sync #13 : 1 other dependent PR (#14 )
• Update wrapper cache for anvil (845337) #23 : 1 other dependent PR (#33 )
• Add UNDERLYING_ADDRESS override for wrapper #17
• Wire anvil-deploy to wrapper script; set signer #9 : 1 other dependent PR (#10 )
• Test wrapper metadata and upgrade/downgrade #8
• Align viem calls and env discovery in tests #26 : 1 other dependent PR (#27 )
• Ensure hardfork=cancun on hardhat network #25
• Add test/type dependencies and refresh bun.lock #24
• Add CFAv1Forwarder field (optional) #12
• Add Superfluid config and deployments scaffold #6 : 1 other dependent PR (#7 )
• Remove legacy lockbox code; rename Tilt resource #5
• Rename package name #3 : 1 other dependent PR (#4 )
• Scaffold project from send-token-upgrade #2
• Initialize README for SuperToken wrapper #1
• main

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