Refine lower-bound reporting and examples

[dhsohn]

Motivation

I want lower-limit binding estimates to remain available for chemical interpretation rather than being presented as statistical warnings solely because they approach the numerical search bound. Very weak binding can be physically meaningful, while the existing active-bound identifiability gate continues to exclude fits that fail that numerical criterion.

I also found that the synthetic CSV generator had no consumer beyond its regeneration instruction. The checked-in deterministic CSV files are sufficient for tutorials, smoke tests, and regression coverage.

I found five tests that duplicated stronger coverage of the same paths or asserted only a low-value sanity condition. Two CLI end-to-end tests also pinned the absence of retired output files instead of focusing on the current HTML report contract. Removing these checks keeps the suite focused on observable and scientific behavior.

Changes

• Removed the report warning emitted when a fitted log10(K) approaches the lower search bound.
• Preserved upper-bound warnings, the active-bound fit gate, information-criterion ranking, and displayed fit results.
• Removed the unused synthetic CSV generator and its regeneration instructions.
• Kept all four deterministic synthetic CSV files, their CLI usage documentation, and CSV-based fit tests.
• Removed five redundant tests whose paths remain covered by stronger CLI, input, and fitting tests.
• Removed four assertions that only checked for retired summary.csv and decision.txt outputs while preserving positive report.html and replicate-report checks.

Verification

• python -m pytest -q — 169 passed.
• python -m ruff check . — passed.
• Focused replacement coverage for the five removed tests — 7 passed.
• Focused CLI end-to-end report checks — 2 passed.
• Focused upper-bound and active-bound checks — 3 passed.
• synthetic_11.csv CLI smoke — generated one report with no lower-bound warning.
• Generator-reference audit — 0 remaining references.
• git diff --check — passed.