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/ui/console.c

@@ -470,10 +470,10 @@ cons_show_wins(gboolean unread)
 
     GSList* curr = window_strings;
     while (curr) {
-        if (g_strstr_len(curr->data, strlen(curr->data), " unread") > 0) {
-            win_println(console, THEME_CMD_WINS_UNREAD, "-", "%s", curr->data);
+        if (g_strstr_len((char*)curr->data, strlen((char*)curr->data), " unread") != NULL) {
+            win_println(console, THEME_CMD_WINS_UNREAD, "-", "%s", (char*)curr->data);
         } else {
-            win_println(console, THEME_DEFAULT, "-", "%s", curr->data);
+            win_println(console, THEME_DEFAULT, "-", "%s", (char*)curr->data);
         }
         curr = g_slist_next(curr);
     }
@@ -491,10 +491,10 @@ cons_show_wins_attention()
 
     GSList* curr = window_strings;
     while (curr) {
-        if (g_strstr_len(curr->data, strlen(curr->data), " unread") > 0) {
-            win_println(console, THEME_CMD_WINS_UNREAD, "-", "%s", curr->data);
+        if (g_strstr_len((char*)curr->data, strlen((char*)curr->data), " unread") != NULL) {
+            win_println(console, THEME_CMD_WINS_UNREAD, "-", "%s", (char*)curr->data);
         } else {
-            win_println(console, THEME_DEFAULT, "-", "%s", curr->data);
+            win_println(console, THEME_DEFAULT, "-", "%s", (char*)curr->data);
         }
         curr = g_slist_next(curr);
     }
@@ -512,7 +512,7 @@ cons_show_room_invites(GList* invites)
     } else {
         cons_show("Chat room invites, use /join or /decline commands:");
         while (invites) {
-            cons_show("  %s", invites->data);
+            cons_show("  %s", (char*)invites->data);
             invites = g_list_next(invites);
         }
     }
@@ -591,7 +591,7 @@ cons_show_caps(const char* const fulljid, resource_presence_t presence)
             win_println(console, THEME_DEFAULT, "-", "Features:");
             GSList* feature = caps->features;
             while (feature) {
-                win_println(console, THEME_DEFAULT, "-", " %s", feature->data);
+                win_println(console, THEME_DEFAULT, "-", " %s", (char*)feature->data);
                 feature = g_slist_next(feature);
             }
         }
@@ -611,10 +611,10 @@ cons_show_received_subs(void)
     if (received == NULL) {
         cons_show("No outstanding subscription requests.");
     } else {
-        cons_show("Outstanding subscription requests from:",
+        cons_show("Outstanding subscription requests from (%d):",
                   g_list_length(received));
         while (received) {
-            cons_show("  %s", received->data);
+            cons_show("  %s", (char*)received->data);
             received = g_list_next(received);
         }
         g_list_free_full(received, g_free);
@@ -782,7 +782,7 @@ cons_show_disco_info(const char* jid, GSList* identities, GSList* features)
             cons_show("  Features:");
         }
         while (features) {
-            cons_show("    %s", features->data);
+            cons_show("    %s", (char*)features->data);
             features = g_slist_next(features);
         }
 
@@ -2297,7 +2297,7 @@ cons_show_themes(GSList* themes)
     } else {
         cons_show("Available themes:");
         while (themes) {
-            cons_show("%s", themes->data);
+            cons_show("%s", (char*)themes->data);
             themes = g_slist_next(themes);
         }
     }
@@ -2315,7 +2315,7 @@ cons_show_scripts(GSList* scripts)
     } else {
         cons_show("Scripts:");
         while (scripts) {
-            cons_show("%s", scripts->data);
+            cons_show("%s", (char*)scripts->data);
             scripts = g_slist_next(scripts);
         }
     }
@@ -2333,7 +2333,7 @@ cons_show_script(const char* const script, GSList* commands)
     } else {
         cons_show("%s:", script);
         while (commands) {
-            cons_show("  %s", commands->data);
+            cons_show("  %s", (char*)commands->data);
             commands = g_slist_next(commands);
         }
     }