feat(codegen,runtime): emit the unary kinds the DSL already exposes

[bigSheep123]

feat(codegen,runtime): emit the unary kinds the DSL already exposes

Fixes #71.

What was wrong

tf.exp, tf.exp2, tf.log, tf.log2, tf.abs, tf.ceil and tf.round are
all reachable from the DSL and all type-infer and evaluate, but _UNARY_TAG
carried rows for only RSQRT, NEG, RELU and SQUARE. Everything else
failed at emission with a bare KeyError: <UnaryKind.LOG: 'log'> — writable and
checkable, but not compilable.

The change

The seven missing runtime functors and their tag rows, following the existing
pattern in unary.cuh.

Two choices worth calling out:

• The transcendentals use the precise <math.h> entries (expf, logf,
  exp2f, log2f) rather than the __-prefixed intrinsics, so a compiled
  kernel agrees with the evaluator's torch oracle instead of being slightly
  faster and slightly different. A kernel that would rather have the intrinsic
  can still reach for it explicitly.
• round uses rintf, which breaks halfway cases to even, matching
  torch.round. roundf rounds them away from zero and would disagree at every
  .5.

CAST and NOT stay absent deliberately, and the table now says so rather than
leaving them looking pending: CAST has its own handler, and NOT is a boolean
operation rather than the float path these functors assume.

Tests

tests/integration/test_unary_codegen.py compiles one kernel per op and
compares against the torch oracle on GPU. Verified to fail on main first —
all seven raise KeyError at emission — and pass after.

The inputs are chosen per op rather than shared: log / log2 get a strictly
positive domain, and round gets a grid landing exactly on .5 boundaries so
the rounding-mode choice above is actually exercised instead of assumed.

Each kernel is a separate top-level function because the compiled artifact is
cached per function — a factory emitting several same-named kernels hands every
op whichever one compiled first.

Verification

pytest tests/ -q     644 passed (main @ e55e4b0)  ->  651 passed (+7 new)

Every .pre-commit-config.yaml hook clean: ruff, spec-rules, spec-refs,
spec-entropy, forward-references, comment-hygiene, no-machine-paths,
english-only, and clang-format over all C++ files.