Don't clobber caller's client_min_messages on install (#4)

The install script began with an unconditional
`SET LOCAL client_min_messages = WARNING`. Because CREATE EXTENSION
runs the whole script in a single transaction, that SET LOCAL applied
for the entire statement -- including any CASCADE that pulls
object_reference in as a dependency -- silently overriding a caller
who had deliberately set a stricter level (e.g. `SET client_min_messages
= error`) to keep install output quiet.

Replace it with a DO block that only raises the floor to WARNING when
the caller's current level is more verbose than WARNING; a stricter
level (warning/error) is left untouched. SET LOCAL inside the DO block
still applies to the rest of the CREATE EXTENSION transaction and
reverts at commit, so it never leaks into the caller's session.

Note: the zzz_build test echoes the install script with source line
numbers, so its expected output shifts by the number of lines this
block adds (+32). It could not be regenerated in place here because
master does not build on modern PostgreSQL with the pgxn-provided
cat_tools; regenerate expected output in the canonical CI environment.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

Author: jnasbyupgrade

sql/object_reference.sql

@@ -1,4 +1,36 @@
-SET LOCAL client_min_messages = WARNING;
+/*
+ * Quiet the NOTICEs this install script emits (e.g. duplicate CREATE ROLE)
+ * without overriding a caller who has deliberately asked for even less output.
+ *
+ * CREATE EXTENSION runs the whole script in one transaction, so a blind
+ * `SET LOCAL client_min_messages = WARNING` clobbers the caller's setting for
+ * the entire statement -- including any CASCADE that pulls this extension in
+ * as a dependency (see issue #4). A caller who set a stricter level such as
+ * ERROR to keep install output quiet would be silently overridden.
+ *
+ * Instead only raise the floor to WARNING; never lower it below the level the
+ * caller chose. SET LOCAL inside a DO block still applies to the rest of the
+ * (CREATE EXTENSION) transaction, and reverts at commit so it does not leak
+ * into the caller's session.
+ */
+DO $$
+DECLARE
+  -- client_min_messages levels ordered least-to-most severe (LOG sorts
+  -- between DEBUG1 and NOTICE for this GUC).
+  c_levels CONSTANT text[] := ARRAY[
+    'debug5', 'debug4', 'debug3', 'debug2', 'debug1'
+    , 'log', 'notice', 'warning', 'error'
+  ];
+BEGIN
+  IF pg_catalog.array_position(
+       c_levels
+       , pg_catalog.lower(pg_catalog.current_setting('client_min_messages'))
+     ) < pg_catalog.array_position(c_levels, 'warning')
+  THEN
+    SET LOCAL client_min_messages = warning;
+  END IF;
+END
+$$;
 \echo This extension must be loaded via 'CREATE EXTENSION object_reference;'
 \echo You really, REALLY do NOT want to try and load this via psql!!!
 \echo It will FAIL during pg_dump! \quit