feat(bindings): tAnd / tOr / tagg_min / tagg_max / tagg_sum aggregates

[estebanzimanyi]

Summary

Adds 5 more skiplist-backed temporal aggregates on top of the infrastructure landed for `tCount` (PR #50):

Aggregate	Inputs	Output
`tAnd(tbool)`	tbool	tbool — per-instant boolean AND
`tOr(tbool)`	tbool	tbool — per-instant boolean OR
`tagg_min(tint)` / `tagg_min(tfloat)`	tint / tfloat	same — per-instant minimum
`tagg_max(tint)` / `tagg_max(tfloat)`	tint / tfloat	same — per-instant maximum
`tagg_sum(tint)` / `tagg_sum(tfloat)`	tint / tfloat	same — per-instant sum

ttext skipped — text merge needs `text_cmp` plumbing not yet wired.

```sql
SELECT tagg_min(t) FROM (VALUES (tint '5@2000-01-01'), (tint '3@2000-01-01')) tt(t);
-- {3@2000-01-01 00:00:00+00}

SELECT tAnd(t) FROM (VALUES (tbool 't@2000-01-01'), (tbool 'f@2000-01-01')) tt(t);
-- {f@2000-01-01 00:00:00+00}
```

Implementation

Factors the boilerplate from `TCountFunction` into a templated functor:

```cpp
template <TempTransfn TRANSFN, Datum (*MERGE_FN)(Datum, Datum), bool CROSSINGS>
struct SkiplistAggFunction { ... };
```

Each aggregate is now one `MakeSkiplistAggregate<&meos_transfn, &merge_fn, crossings>(input, output)` instantiation.

The merge functions used by `Combine` (`datum_and`, `datum_or`, `datum_min_int32`, `datum_max_int32`, `datum_sum_int32`, `datum_min_float8`, `datum_max_float8`, `datum_sum_float8`) are not exported from MEOS, so local equivalents are provided in this file. Float8 conversion goes through an aliased union to handle the IEEE 754 bit-pattern stored in `Datum`.

Naming note (`tagg_*` instead of `tMin`/`tMax`/`tSum`)

`Tmin` and `Tmax` are already registered as scalar time-min / time-max accessors on tbox / stbox (`src/temporal/tbox.cpp` line 396, 414, `src/geo/stbox.cpp` line 257, 302). DuckDB's catalog is case-insensitive at the name level, so registering an aggregate named `tMin` would lookup-collide with the existing scalar and trigger an `ALTER` path that `CreateAggregateFunctionInfo` doesn't implement (`GetAlterInfo not implemented for this type`) — extension fails to load.

The `tagg_*` prefix sidesteps the collision. A future cleanup could rename the existing scalars (e.g. to `time_min(tbox)` / `time_max(tbox)`) and reclaim the `tMin` / `tMax` / `tSum` names if MobilityDB-name parity is preferred.

Stacked on

• feat(bindings): aggregate function infrastructure — extent(span) for all 5 span types #47 (AggregateFunction infra)
• feat(bindings): extend extent(*) to spanset and set surfaces #48 (extent spanset/set)
• feat(bindings): extent(tnumber) → tbox + bundle extent overloads in one set #49 (extent tnumber)
• feat(bindings): tCount(temporal) aggregate — first skiplist-backed aggregate #50 (tCount + skiplist-backed pattern)

Test plan

• All 8 aggregate-overloads produce correct values
• Mixed t/f tbool inputs handled correctly for tAnd/tOr
• No segfaults (skiplist destructor pattern from feat(bindings): tCount(temporal) aggregate — first skiplist-backed aggregate #50)
• Local extension loads cleanly

[estebanzimanyi]

Consolidated into #60 (aggregate cluster squash). The full chain of aggregate work is now reviewable as a single PR; this branch's commits are preserved in #60's history. Closing to minimize the review queue.