Phase 2 cleanup: remove residual `cast()` calls in `_pagination.py` and
`# type: ignore` comments in `_http.py` so the SDK has zero type-system
escapes outside generated files (P5).

Made-with: Cursor

* P1 (response strict): add `parse_strict_envelope` helper to
  `_validation.py` so endpoints with nullable `data` (today only
  GET /api/v1/deploy/lock) reject unknown top-level envelope keys
  without forcing the resource layer to declare a `BaseModel`
  subclass (which would trip the new `disallow_any_explicit`).
* P3 (validation surfaces): narrow broad `except Exception` in
  `_pagination.py` to `ValidationError`, and pass the inner errors
  + cause into `DevhelmValidationError` so callers can route on
  field-level failures and stack traces survive.
* P5 (no-Any in user-facing layer): enable
  `disallow_any_explicit = true` globally with explicit overrides
  for the JSON-boundary modules (`_errors`, `_http`, `_pagination`,
  `_validation`, `_generated`). Renamed the typing test to
  `test_resource_layer_is_any_free` and rewrote it against the new
  contract.
* Lock in `RootModel` strictness with a focused suite covering both
  the scalar wrapper (`SubscribedEvent`) and the discriminated
  union (`CheckTypeDetailsDto`); these were silently skipped by
  `inject_strict_config` and thus never directly verified.
* Lock in `parse_strict_envelope` semantics (extras forbidden,
  optional null, structured Pydantic error propagation) in a new
  `tests/test_validation_helpers.py`.

Made-with: Cursor

CI's `ruff format --check` was failing on 7 files that hadn't been
reformatted since the last formatter rule update. Applied the formatter.

Also fixes a latent brittleness: `test_typing.py` allow-listed the one
documented `# type: ignore` by full `path:lineno: line` triple, so any
unrelated reflow above the suppression site (like this very format pass
shifting line 126 → 122 in `_validation.py`) silently turns the test red
on changes that have nothing to do with type ignores.

The allow-list is now keyed on `(relative_path, stripped_line)` —
adding/removing/moving suppressions still reds the test, but unrelated
formatting churn doesn't. The error message keeps the full
`file:line:` offender list for fast diagnosis.

Verified: ruff format --check, ruff check, mypy, and `pytest` (700
passed) all green locally.

Made-with: Cursor