fix: CWE-134 format string audit and compiler hardening

Security:
Fix CWE-134 in iq.c: user-controlled string passed as format argument
Add G_GNUC_PRINTF annotations to all variadic printf-like wrappers
in ui.h, log.h and http_common.h
Compiler flags (configure.ac):

Replace basic -Wformat/-Wformat-nonliteral with -Wformat=2
Add -Wextra, -Wnull-dereference, -Wpointer-arith,
-Wimplicit-function-declaration, -Wundef, -Wfloat-equal,
-Wredundant-decls, -Walloc-zero
Add -fstack-protector-strong, -fno-common, -D_FORTIFY_SOURCE=2
Add GCC-specific flags via AC_COMPILE_IFELSE: -Wlogical-op,
-Wduplicated-cond, -Wduplicated-branches, -Wstringop-overflow,
-Warray-bounds=2
Suppress noisy -Wextra sub-warnings: -Wno-unused-parameter,
-Wno-missing-field-initializers, -Wno-sign-compare,
-Wno-cast-function-type
Remove AM_CFLAGS/CFLAGS duplication
Bug fixes found by new warnings:

chatlog.c: non-MUCPM redact path passed resourcepart instead of NULL
rosterwin.c: merge duplicated if/else branches into single condition
omemo.c: redundant else-if in omemo_automatic_start; remove
unnecessary scope block and goto, use early return
console.c: pointer compared to integer 0 instead of NULL
stanza.c: increase pri_str/idle_str buffers from 10 to 12 bytes
(INT_MIN = -2147483648 needs 12 bytes including NUL)
vcard.c: NULL guard for filename before g_file_set_contents
api.c: broken log_warning() calls with extra format argument
Format mismatch fixes:

chatwin.c: Jid* → char* for %s
connection.c: %x → %lx for long flags
cmd_funcs.c: %d → %zu for size_t; cast gpointer to char* for %s
cmd_defs.c: %d → %u for g_list_length() return (guint)
iq.c: barejid → fulljid for from_jid
console.c, mucwin.c, privwin.c, account.c, omemo.c, presence.c:
gpointer → (char*) casts for %s
Const-correctness and cleanup:

database.c: const for type, query, sort variables
form.c/xmpp.h: const for form_set_value parameter
files.c: refactor to early return, eliminating NULL logfile path
muc.c/muc.h: remove meaningless top-level const on return type
common.c: const for URL string literal
Remove stale declarations: cons_show_desktop_prefs (ui.h),
connection_set_priority (connection.h),
omemo_devicelist_configure_and_request (omemo.h)
test_common.c: add currb NULL check to silence -Wnull-dereference
Tooling (check-cwe134.sh):

Reduce from 5 checks to 2 (checks 1-3 redundant with -Wformat=2)
Check 1: verify known wrappers have G_GNUC_PRINTF attribute
Check 2: auto-detect unannotated variadic printf-like functions
Match both const char* and const gchar* in variadic patterns

Author: jabber.developer2 <jabber.developer2@jabber.space>

src/config/account.c

@@ -189,7 +189,7 @@ account_eval_password(ProfAccount* account)
 
     int exit_status = pclose(stream);
     if (exit_status > 0) {
-        log_error("Command for `eval_password` returned error status (%s).",
+        log_error("Command for `eval_password` returned error status (%d).",
                   exit_status);
         return FALSE;
     } else if (exit_status < 0) {

src/config/files.c

@@ -114,30 +114,26 @@ gchar*
 files_get_log_file(const char* const log_file)
 {
     auto_gchar gchar* xdg_data = _files_get_xdg_data_home();
-    GString* logfile;
 
     if (log_file) {
         auto_gchar gchar* log_path = g_path_get_dirname(log_file);
         if (!create_dir(log_path)) {
             log_error("Error while creating directory %s", log_path);
         }
-
-        logfile = g_string_new(log_file);
-    } else {
-        logfile = g_string_new(xdg_data);
-        g_string_append(logfile, "/profanity/logs/profanity");
-
-        if (!prefs_get_boolean(PREF_LOG_SHARED)) {
-            g_string_append_printf(logfile, "%d", getpid());
-        }
-
-        g_string_append(logfile, ".log");
+        return g_strdup(log_file);
     }
 
+    GString* logfile = g_string_new(xdg_data);
+    g_string_append(logfile, "/profanity/logs/profanity");
+
+    if (!prefs_get_boolean(PREF_LOG_SHARED)) {
+        g_string_append_printf(logfile, "%d", getpid());
+    }
+
+    g_string_append(logfile, ".log");
+
     gchar* result = g_strdup(logfile->str);
-
     g_string_free(logfile, TRUE);
-
     return result;
 }