refactor(quickadapter): state-form prose and harmonization follow-up (#100)

refactor(quickadapter): state-form prose and harmonization follow-up (#100)

Consolidates content + harmonization + Python-idiom follow-up findings
from the 4-axis review of `add1fb7..7c8197b` (PRs #90, #94, #95, #96,
#97, #98, #99 + 4 style commits + 1 chore version-constant update).

Prose state-form (`Utils.py`, `QuickAdapterRegressorV3.py`):
- `_normalize_label_column_name` docstring: ``Raises ValueError when
  the result contains `&` or `%` after sigil strip``.
- Deprecated-config-key warning aligns with the sibling pattern at
  the adjacent branch: ``f"{old_path!r} is deprecated, use
  {new_path!r} instead"``.
- `sanitize_and_renormalize` docstring states ``mean(out) == 1`` as the
  rescale invariant.
- Optuna-label throttle log reads ``callback throttled,
  {N} candles until next emission``.
- Fit-live-predictions warmup log reads ``Fit live predictions not
  warmed up: {N} candles until warmup completion``.

Docstrings on validator/composer helpers (3 functions lacking a
docstring at HEAD):
- `_apply_support_policy`: documents the ``policy='raise'`` /
  ``policy='fallback'`` dispatch contract.
- `_compose_train_weights_with_support`: documents the support-gating
  flow (None-label-weights branch routes through
  ``_apply_support_policy`` when ``strategy != 'none'``; main branch
  composes and validates the summary against three thresholds).
- `_validate_optuna_label_best_params`: enumerates the rejection
  paths and the optional ``expected_selection_metadata`` drift gate.

Harmonization (post-merge carry-over):
- `LABEL_WEIGHT_SUFFIX` renamed to `_LABEL_WEIGHT_SUFFIX`
  (no external consumer; symmetric with
  `_LABEL_KNOWN_AT_LOOKAHEAD_SUFFIX`).
- `safe_distribution_fit` call-site contexts harmonized with the
  PR #97 / PR #99 ``[<pair>] <event>`` convention:
  `f"[{pair}] di_values_weibull_fit"` and
  `f"[{pair}] label_norm_fit:{label_col}"`.

Python idioms:
- `_adapt_label_generator` rejects any 3rd positional parameter
  whose name is not ``logger``, regardless of whether the parameter
  is required or has a default. A defaulted non-``logger`` 3rd
  positional raises ``ValueError`` at registration. The 3-arg
  pass-through is reached only when ``positional[2].name == "logger"``.
- `_build_sample_weight_inputs` switches the two `logger.debug`
  calls to lazy ``%s`` formatting so the f-string body is not
  materialized when the debug level is disabled.