fix: preserve guarded sample lifecycle

[Jammy2211]

Summary

Keep the new model-parameter guards, while making every stored-sample consumer treat guard failures as rejected historical points instead of fatal infrastructure errors.

This addresses the two independent regressions behind the blocked nightlies:

• PyAutoFit fix: handle rejected final samples in test mode 1 #1463 rebuilt rejected test-mode fits as a bare SamplesPDF, losing the original sampler type, metadata, and factor-graph/per-analysis model structure.
• fix: validate profile constructor inputs (#440 — B9, B11, B12) + B10 tolerance pin PyAutoGalaxy#566 and fix: resample invalid profile parameters PyAutoGalaxy#568 made live samplers resample guard failures, but stored-sample replay and aggregators still materialized invalid historical points without an equivalent rejection path.

Changes

• Preserve samples.model, the concrete samples class, and samples_info when test-mode recovery replaces a rejected final sample.
• For instance materialization, fall back from an invalid maximum-likelihood historical point to the next valid point.
• Retry PDF draws rejected by FitException, with a bounded attempt limit and a clear SamplesException if no valid point exists.
• Skip FitException-invalid points in weighted aggregator replay while keeping samples and weights aligned.
• Reconstruct aggregator points through the stored model so shared factor-graph children remain intact.
• Catch only FitException; unrelated programming errors still propagate.

The PyAutoGalaxy guards themselves are unchanged.

Regression coverage

Adds coverage for:

• factor-graph per-analysis children
• preservation of sampler subtype and metadata
• invalid historical maximum-likelihood fallback
• bounded PDF redraw and all-invalid failure
• weighted aggregator filtering and weight alignment
• shared factor-graph children during aggregator replay
• propagation of non-FitException errors

Validation

• Focused regression suite: 48 passed
• Full PyAutoFit suite: 1723 passed, 2 skipped
• git diff --check: clean