Lucidly syUSD idle-balance adapter for agent wallets (refresh of #20)

[abhicris]

Problem

Closed issue #20 specified a Lucidly syUSD auto-park flow but went stale before the partner conversation matured. The shape is right; the integration timing is now live. This issue replaces #20 with a current-spec version aligned to the 2026-06-01 partnership map (validator-slot + adapter contract together).

Agent wallets sit on idle CR8-USD / USDC between settlements. At any realistic agent payment volume (hundreds of agents, single-digit USD per settlement), 70-95% of the float is idle. Parking that float into Lucidly's syUSD vault earns yield with zero behavioral change at the agent layer.

Proposed Approach

1. contracts/adapters/LucidlyAdapter.sol wraps the ILucidlyVault interface. Per-wallet config:
   • idle_target_bps (e.g. 8000 = 80% parked, 20% liquid buffer)
   • unpark_threshold_bps (when liquid drops below this, pull from vault before next tx)
2. Auto-rebalance hook in AgentEscrow.release and x402_middleware.settle: after every settlement, evaluate liquid buffer vs target. If liquid > target + 5%, deposit excess. If liquid < target - 5%, withdraw from vault.
3. switchboard/adapters/lucidly.py Python client mirror — same logic at the off-chain switchboard layer so non-EVM-native agents can use it.
4. Realized APY card: weekly cron emits a per-wallet realized_30d_apy JSON blob to a public surface. This is the disclosure that closes the loop on the Lucidly co-marketing (per the partnership roadmap).
5. No yield without slippage cap: if Lucidly vault entry slippage exceeds 25 bps, skip the park and log. Avoids the "yield surface looks great until you actually try to enter" trap.

Acceptance Criteria

• LucidlyAdapter.sol deployed against testnet Lucidly vault
• Python client mirrors the same idle_target_bps / unpark_threshold_bps config
• Realized 30d APY card published weekly to a public switchboard surface
• Slippage cap enforced; vault entries above 25 bps skipped + logged
• End-to-end test: 100 simulated settlements over 30 days, target buffer maintained, no rug from vault entry slippage

References

• Issue Lucidly syUSD auto-park for idle agent balances #20 — Lucidly syUSD auto-park (CLOSED, superseded by this)
• internal: see Lucidly partnership memo + stress-test 2026-06-01 section 3.6
• Lucidly syUSD vault interface at kcolbchain/stablecoin-toolkit