ty: re-enable the nine blanket-ignored rules with per-file ignores

[jayhesselberth]

Tier P3 · effort M · from the 2026-09-13 review (CLI F7)

pyproject.toml [tool.ty.rules] ignores unresolved-attribute,
unresolved-import, possibly-missing-attribute, invalid-argument-type,
invalid-method-override, not-subscriptable, no-matching-overload,
too-many-positional-arguments, missing-argument, call-non-callable.
uvx ty check src/leech/ reports "All checks passed"; with those rules as
warnings it reports 218 diagnostics (136 invalid-argument-type, 36
unresolved-attribute, 15 call-non-callable, 10 possibly-missing-attribute,
9 invalid-method-override, 6 not-subscriptable, 3 missing-argument, 2
too-many-positional-arguments). The two at signal_refine.py:733,736 are the
union-dispatch false positive the config comment names; the rest are
unexamined. CI runs uvx ty at latest (ci.yml:53) while the dev pin is
ty>=0.0.64 (lock 0.0.78).

Acceptance criteria

• The nine rules are enabled globally; each remaining false positive carries a # ty: ignore[rule] with a one-line reason; real defects found on the way are fixed in separate small commits (list them in the PR).
• CI pins ty to the locked version (uv run ty, not uvx ty).
• uv run ty check src/leech/ passes with zero diagnostics and no blanket ignores.

Non-goals

• Typing tests/.