Fix coin-ops free-inventory double-count and buffer-raid splits

[hoffmang9]

Summary

• Inventory bucket scans now exclude durable maker coin-id watches (free clips only), with freshness cache keyed by watch fingerprint so posts invalidate without Coinset WS activity.
• Effective sell counts credit live sells toward target only (strip same-cycle newly_executed from the pre-strategy snapshot), so open Direct makers no longer look like full target+buffer coverage.
• Low-watermark splits use SplitSourceProtection::for_low_watermark_split (target-only, full-vault including watched makers) so excess/buffer exact clips can fund smaller-rung deficits; ADR 0024 records the policy.

Test plan

• cargo test -p greenfloor-engine --lib effective_counts
• cargo test -p greenfloor-engine --lib shape_protection
• cargo test -p greenfloor-engine --lib inventory_freshness
• cargo test -p greenfloor-engine --lib eco181_shape_table
• On john-deere after deploy: BYC sell ladder fills the missing size-10 (split from free size-25) instead of looping insufficient cat coins / excess-combine skips