ci: add PostgreSQL 19beta1 to build/test matrix, bump minor versions

[sfc-gh-dachristensen]

Summary

Adds PostgreSQL 19beta1 as a first-class target across the dev container, CI, install script, and the C codebase. After this lands, every extension compiles against PG
19beta1, the docker images build green, and the CI matrix exercises 19 alongside 16/17/18.

This PR has two halves:

1. Infrastructure — wire 19beta1 into the Dockerfile, CI matrices, install.sh, and docker docs/Taskfile, plus bump existing PG minors and a couple of dependency
   versions required for PG19.
2. Code-level fixes — adjust the extensions and pgduck_server so they compile cleanly against PG19, version-gated behind #if PG_VERSION_NUM >= 190000.

Infrastructure changes

• PG minor bumps: 16.14 / 17.10 / 18.4
• PG 19beta1 added to docker/Dockerfile, install.sh, and docker docs/Taskfile.
• PostGIS 3.6.0 → 3.6.3 — 3.6.0 fails to build against PG19 (gserialized_typmod.c: INT_MIN/INT_MAX undeclared); upstream fix is PostGIS commit a7c7a83
  ("Avoid build issue on PG19"), first released in 3.6.1.
• pg_cron: switched to the postgresql-19 branch from CyberDem0n's fork (citusdata/pg_cron PR pg_lake_copy: reject multidimensional arrays in COPY TO before CSV serialization #430) until the PG19 patch is merged upstream. The patch is
  backward-compatible with PG 16/17/18.
• bzip2 added to the almalinux and debian dep lists — the 19beta1 source ships as .tar.bz2.

CI matrix changes

• build-and-install-{almalinux,debian}: [16, 17, 18, 19]
• test-check, test-check-pg-lake-table, test-isolation: [17, 18, 19]
• test-installcheck-postgres: [16, 17, 18, 19]
• test-upgrade: added pairs 17-19, 18-19, 16-19
• test-installcheck and test-installcheck-pg-lake-table remain [16]

PG19 matrix legs are marked continue-on-error so any remaining PG19-specific test failures surface in CI without blocking required checks. The build-and-install-*
jobs flip fail-fast: false so a PG19 issue does not cancel the 16/17/18 legs.

Drive-by

Oracle's /java/21/latest tarball started bumping past jdk-21.0.10, which broke the debian image build with cannot stat '/usr/lib/jvm/jdk-21.0.10'. The Dockerfile
now reads the top-level directory from the tarball instead of hardcoding the patch version.

Code-level fixes

PG19 dropped a number of transitive header includes and reshaped a handful of APIs. Most of the diff is just adding the explicit #include that PG18 was getting
transitively. Real API changes are version-gated.

Header reorg

PG19 dropped these from common transitive include paths; affected .c/.h files now include them explicitly:

Header	Why
utils/tuplestore.h	was reached via nodes/execnodes.h
access/htup_details.h	was reached via executor/tuptable.h
utils/hsearch.h	HASHCTL, hash_create, hash_search, hash_seq_*
catalog/pg_type_d.h	TEXTOID, INTERVALOID, etc.
utils/wait_event.h	WAIT_EVENT_CLIENT_READ
utils/timestamp.h	DatumGetTimestampTz, TimestampTzGetDatum, IntervalPGetDatum
storage/lock.h	LockAcquire, LockAcquireResult, LOCKTAG
storage/fd.h	AllocateFile, FreeFile, OpenTemporaryFile, FileClose
<math.h>	isnan, isinf

API changes

Wrapped behind #if PG_VERSION_NUM >= 190000:

• LWLockNewTrancheId() now requires a name argument; the separate LWLockRegisterTranche() helper is gone.
• ShmemInitHash() collapsed init_size / max_size into a single nelems.
• SIG_IGN → PG_SIG_IGN (pqsigfunc-typed sentinel) when used with pqsignal().
• pg_plan_query() and planner_hook_type gained a trailing ExplainState * argument.
• DefineIndex() gained a leading ParseState * argument.
• bits16 type was removed; format_type_extended flags are now uint16.
• utils/dynahash.h was deleted (only declared my_log2); the unused includes are wrapped behind PG_VERSION_NUM < 190000.
• CopyFormatOptions.binary / .csv_mode were replaced by an enum .format field. Wrapped behind CopyOptsIsBinary / CopyOptsIsCsvMode macros in pg_compat.h
  so callers keep the older names.
• CopyHeaderChoice enum was removed; header_line is now a plain int with COPY_HEADER_TRUE/FALSE/MATCH constants. Reintroduced the typedef locally so the
  exported API signature stays stable.
• numeric_{int4,add,sub,mul,div,mod}_opt_error() renamed to _safe() variants and switched from a bool * error flag to an ErrorSaveContext * (soft-error
  API). Wrapped via shims in pg_compat.h that preserve the older signatures.

Build flag

• pgduck_server's -std=c11 → -std=gnu11 so PG19's c.h (which uses typeof and static_assert unconditionally) compiles. PG itself uses the GNU dialect for the
  same reason.

Drive-by

pgduck_server is a frontend program; the unused #include "nodes/nodes.h" in numutils.h started failing because PG19 changed nodes.h to use Datum in extern
declarations. Removed the vestigial include.

What is expected to work

• All eight extensions and pgduck_server compile cleanly against PG 19beta1 locally.
• Docker images build successfully on both almalinux and debian for PG 19beta1.
• PG 16/17/18 build/test legs unaffected (no regressions from minor bumps or PostGIS/pg_cron source changes).
• PG19 test legs may still surface failures from runtime behavior changes (planner output, error messages, EXPLAIN format, etc.); those are scoped out of this PR
  and tracked via continue-on-error. Follow-up will tighten the matrix as test failures are addressed.

Test plan

• CI green for PG 16/17/18 (no regressions)
• PG19 image builds successfully end-to-end on both almalinux and debian
• PG19 build-and-install legs pass
• PG19 test legs report status (pass or fail) without blocking required checks
• Spot-check ./install.sh --build-postgres --pg-version 19
• Once the matrix stabilizes, drop the continue-on-error overrides in a follow-up

[sfc-gh-dachristensen]

Closing in lieu of #404 (shares a lot of commit lineage anyway).