Archiver crashes on year 10000+ partition boundaries

[imtiazqa]

ParseBoundExpr uses Go's time.Parse with a fixed 4-digit year format. PostgreSQL returns "10000-06-01 00:00:00+00" for year 10000+ partition bounds. Go's parser rejects it, crashes the archiver, and skips all tables that come after it alphabetically.

Steps to reproduce:

1. Create a partitioned table with a year 10000 partition:

CREATE TABLE public.yr10k_test (...) PARTITION BY RANGE (ts);
CREATE TABLE public.yr10k_test_p_10000_06 PARTITION OF public.yr10k_test
  FOR VALUES FROM ('10000-06-01') TO ('10000-07-01');
INSERT INTO public.yr10k_test (ts, payload)
  SELECT '10000-06-15 00:00:00+00', 'row-'||i FROM generate_series(1,50) i;

2. ./bin/archiver register --table yr10k_test
3. ./bin/archiver

Actual result:

[yr10k_test] archive cycle: ensure current partition: parse bounds for
yr10k_test_p_10000_06: parse lower bound: unrecognized timestamp format:
"10000-06-01 00:00:00+00"
Archiver exits 1.

Expected result:
Archiver handles year 10000+ partition bounds without crashing. Either archives the partition or skips it with a clear warning.

[imtiazqa]

Also reproduced with the max PostgreSQL timestamp (year 294276). Same failure:

parse lower bound: unrecognized timestamp format: "294276-11-01 00:00:00+00"
Steps:

CREATE TABLE public.maxts_test (...) PARTITION BY RANGE (ts);
CREATE TABLE public.maxts_test_p_294276_11 PARTITION OF public.maxts_test
FOR VALUES FROM ('294276-11-01') TO ('294276-12-01');
INSERT INTO public.maxts_test (ts, payload)
SELECT '294276-11-15 00:00:00+00', 'row-'||i FROM generate_series(1,50) i;
Any timestamp with more than 4 digits in the year hits this. The fix needs to handle years with arbitrary digit width, not just 5-digit years.