feat(bindings): tnumber unary functions (abs, derivative, degrees, radians)

[estebanzimanyi]

Summary

Adds 6 ScalarFunction registrations for unary tnumber functions:

SQL	MEOS
abs(tint) -> tint	tnumber_abs
abs(tfloat) -> tfloat	tnumber_abs
derivative(tfloat) -> tfloat	temporal_derivative
degrees(tfloat) -> tfloat	tfloat_degrees(t, false)
degrees(tfloat, BOOL) -> tfloat	tfloat_degrees(t, normalize)
radians(tfloat) -> tfloat	tfloat_radians

Temporal_derivative was already declared and implemented in src/temporal/temporal_functions.cpp but was never registered; this PR registers it without duplicating the body.

Implementation reuses the templated wrapper helpers from PR #27 (TemporalUnary / TemporalBinaryV<bool>).

Smoke test

SELECT abs(tint '[-1@2000-01-01, 2@2000-01-02]');
-- [1@2000-01-01 00:00:00+00, 2@2000-01-02 00:00:00+00]

SELECT derivative(tfloat '[1@2000-01-01, 4@2000-01-04]');
-- Interp=Step;[1.157e-05@..., 1.157e-05@...]

SELECT degrees(tfloat '[0@2000-01-01, 3.14159@2000-01-02]');
-- [0@..., 179.9998479605043@...]

SELECT radians(tfloat '[0@2000-01-01, 180@2000-01-02]');
-- linear-radians value sequence

Test plan

• make release then TZ=UTC ./build/release/test/unittest "<proj>/test/*" — full suite passes.
• After PR feat(bindings): tnumber arithmetic operators (+, -, *, /) — 24 registrations #29 (tnumber arithmetic) and this lands, PR test(parity): batch 2 — boolops / textfuncs / compops / posops / aggfuncs #24's 026_tnumber_mathfuncs.test skip block fully unwraps.

Dependencies

Stacked on PR #29 (tnumber arithmetic). Merge order: #27 → #29 → this.

[estebanzimanyi]

Consolidated into #43 (tnumber numeric functions — arithmetic + unary + distance).