sqlite: map the full practical C API

src/db/sqlite.sx grows from the P5.1 subset (~19 fns) to the complete
practical surface (~100): open_v2 + flags, extended errcodes +
error_offset, txn_state/autocommit, changes64/total_changes64, limits,
the full bind/column families (double/blob/zeroblob), parameter and
column introspection (built with SQLITE_ENABLE_COLUMN_METADATA),
table_column_metadata, statement introspection (sql/expanded_sql/
readonly/busy/isexplain/status), incremental blob I/O (SqliteBlob),
online backup (SqliteBackup + sqlite_backup_run), serialize/
deserialize, and library utilities (complete, strglob/strlike/stricmp,
randomness, memory, compileoptions). One variant per duplicate family
(modern/64-bit preferred; bind_text/blob keep the 32-bit length forms
that skip text64's encoding arg). Not bound, by design: callback-taking
APIs (hooks/UDFs/collations need C->sx callbacks), sqlite3_value_*
(UDF-coupled), varargs config, UTF-16, and subsystems this build omits
— the boundary list lives in the module header and vendor README.

rename.h is now GENERATED by make into build/vendor/ from the bindings'
#foreign names — src/db/sqlite.sx is the single source of truth and the
rename list cannot drift (checked-in vendor/sqlite/rename.h removed).

make test 21/21 (new: sqlite_api.sx — 15 cases over every wrapper
family, including a blob round trip with interior NULs, UNIQUE
constraint extended errcodes, txn_state through BEGIN IMMEDIATE,
backup db->db, and a serialize->deserialize round trip).

KNOWN sx BOUNDARY (filed as a followup): 'if !e' on an error binding
evaluates true even when the error is set — negated error logic in
tests routes through plain bools.

Makefile

@@ -16,19 +16,29 @@ DIST  := src/dist.sx
 # products in two DIRECTORIES — the macOS linker prefers a dylib over an
 # archive in the same -L directory, and `sx build` must link the static
 # copy while `sx run` (the test runner) dlopens the dylib.
+#
+# rename.h is GENERATED from the bindings: every `dist_sqlite3_*` symbol
+# named in src/db/sqlite.sx gets a #define, so the rename list and the
+# bound surface cannot drift (see the README for why renaming exists).
 VENDOR_DIR  := $(BUILD_DIR)/vendor
 SQLITE_SRC  := vendor/sqlite/sqlite3.c
 SQLITE_DEFS := -DSQLITE_DQS=0 -DSQLITE_THREADSAFE=0 -DSQLITE_DEFAULT_MEMSTATUS=0 \
                -DSQLITE_OMIT_DEPRECATED -DSQLITE_OMIT_SHARED_CACHE \
-               -DSQLITE_LIKE_DOESNT_MATCH_BLOBS \
-               -include vendor/sqlite/rename.h
+               -DSQLITE_LIKE_DOESNT_MATCH_BLOBS -DSQLITE_ENABLE_COLUMN_METADATA \
+               -include $(VENDOR_DIR)/rename.h
 
-$(VENDOR_DIR)/libsqlite3.a: $(SQLITE_SRC) vendor/sqlite/sqlite3.h vendor/sqlite/rename.h
+$(VENDOR_DIR)/rename.h: src/db/sqlite.sx
+	@mkdir -p $(VENDOR_DIR)
+	@{ echo '/* GENERATED by make from src/db/sqlite.sx — do not edit. */'; \
+	   grep -o '"dist_sqlite3_[a-z0-9_]*"' src/db/sqlite.sx | tr -d '"' | sort -u | \
+	   sed 's/^dist_\(.*\)/#define \1 dist_\1/'; } > $@
+
+$(VENDOR_DIR)/libsqlite3.a: $(SQLITE_SRC) vendor/sqlite/sqlite3.h $(VENDOR_DIR)/rename.h
 	@mkdir -p $(VENDOR_DIR)
 	cc $(SQLITE_DEFS) -O2 -c $(SQLITE_SRC) -o $(VENDOR_DIR)/sqlite3.o
 	ar rcs $@ $(VENDOR_DIR)/sqlite3.o
 
-$(VENDOR_DIR)/jit/libsqlite3.dylib: $(SQLITE_SRC) vendor/sqlite/sqlite3.h vendor/sqlite/rename.h
+$(VENDOR_DIR)/jit/libsqlite3.dylib: $(SQLITE_SRC) vendor/sqlite/sqlite3.h $(VENDOR_DIR)/rename.h
 	@mkdir -p $(VENDOR_DIR)/jit
 	cc $(SQLITE_DEFS) -O2 -dynamiclib $(SQLITE_SRC) -o $@