fix: propagate mutable list replacements

[akonwi]

Context

• Fixes Silent data loss: list.push/prepend through a mut [T] parameter never reaches the caller (no diagnostic) #339.
• Native mut [T] parameters previously copied Go slice descriptors, so push, prepend, and whole-list assignment silently failed to update the caller.
• Mutable-reference semantics require mutations to remain visible through aliases, while foreign Go signatures must retain their exact slice ABI.

What's changed

• Lower native mutable-list references as pointers to slice descriptors.
• Preserve the reference through forwarding, aliases, closures, function values, and generic functions.
• Keep foreign Go ABI list parameters value-shaped as []T.
• Reject descriptor-rebinding operations on foreign slice references while allowing independently owned value copies to grow.
• Preserve foreign-ABI provenance through checker specialization and AIR lowering.
• Amend ADR 0040 and ADR 0045 to document the native/foreign representation boundary.

Validation

• cd compiler && go test ./... -count=1
• gopls check on all changed Go files; only pre-existing redundant-break hints remain.
• git diff --check
• Downstream checks/builds and 158 tests passed across Tinear, Migrate, SQL, Maestro, and Dram.
• Focused code review completed with no remaining material findings.

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Project	Deployment	Actions	Updated (UTC)
ard-lang-dev	Ready	Preview, Comment	Jul 24, 2026 10:23pm