Fix adaptive resource bind lifetimes

[stefanmaierhofer]

Fixes #134

Summary

• Retain one acquired reference to the selected adaptive resource until the binding's final Release or ReleaseAll, while balancing every outer input acquisition.
• Acquire and evaluate replacement branches before publication, serialize lifecycle transitions, and recover cleanly from mapping, acquisition, evaluation, retirement, and notification failures.
• Preserve render-token propagation, shallow input equality, unchanged-branch reuse, dependency-edge ownership, and the allocation-free steady-state GetValue path.
• Cover bind, bind2, and bind3 with backend-independent ownership, switching, exception, reentrancy, and concurrency regressions; clarify the public lifecycle documentation.

Validation

• 23 focused adaptive-resource tests passed, including repeated concurrency runs.
• Complete non-Windows Debug and Release builds passed with no warnings or errors.
• Paired warmed Release benchmarks (median of five processes):

Workload	Before	After	Change	Allocation
Steady-state GetValue	25.710 ns	26.392 ns	+2.65%	0 B -> 0 B
Acquire/materialize/release	510.222 ns	495.364 ns	-2.91%	464 B -> 464 B
Changed-inner switch	751.808 ns	787.337 ns	+4.73%	928 B -> 928 B
Unchanged-inner switch	509.334 ns	470.974 ns	-7.53%	~472 B -> 464 B

The common paths remain neutral within run-to-run variation, and steady-state reads remain allocation-free.