fix(ci): unbreak the ESP32 static analysis gate after the cppcheck 2.20 jump (#11777)

Every PR targeting develop has been red since 2026-09-07 on the seven ESP32
check jobs, while the nRF52, RP2040 and STM32 jobs pass on identical source.

gh-action-firmware#61 moved the ESP32 container images onto the pioarduino
core. Its esp32 platform ships its own tool-cppcheck 2.20.1 and reinstalls it
over anything the repo pins, so ESP32 now analyses with cppcheck 2.20 while
every other platform still resolves platformio/tool-cppcheck 1.21100.230717,
i.e. 2.11. 2.20 parses far more of this tree than 2.11 ever managed, so checks
that were always enabled fired for the first time: 388 defects, ESP32 only.

#11776 cleared the two unknownMacro errors. Of the 386 left, two are worth
acting on and are fixed rather than suppressed:

  * SerialModule dereferenced a null Position in NMEA/CALTOPO mode. `decoded`
    stays NULL when pb_decode_from_bytes() fails, but printWPL() was called
    with *decoded regardless, so a malformed position payload on our portnum
    crashed the node. Emit the waypoint only on a successful decode.
  * InkHUD's 12-hour clock passed a signed 12 to a %u conversion.

The rest are style and performance suggestions - functionStatic and the
const-correctness family account for 351 of them. Suppress those check ids so
the gate means the same thing on every platform again, scoping the one-off
ones to their file so a new occurrence elsewhere still fails. Burning them
down is worth doing deliberately, not under a CI outage.

Verified in the CI container images: all seven previously failing ESP32
environments pass, and rak4631, tracker-t1000-e and t-echo-plus still pass
under cppcheck 2.11.

src/graphics/niche/InkHUD/Applet.cpp

@@ -635,7 +635,7 @@ std::string InkHUD::Applet::getTimeString(uint32_t epochSeconds)
         // Format the clock string, either 12 hour or 24 hour
         char clockStr[11];
         if (config.display.use_12h_clock)
-            sprintf(clockStr, "%u:%02u %s", (hour % 12 == 0 ? 12 : hour % 12), min, hour > 11 ? "PM" : "AM");
+            sprintf(clockStr, "%u:%02u %s", (hour % 12 == 0 ? 12u : hour % 12), min, hour > 11 ? "PM" : "AM");
         else
             sprintf(clockStr, "%02u:%02u", hour, min);
 

src/modules/SerialModule.cpp

@@ -408,17 +408,14 @@ ProcessMessage SerialModuleRadio::handleReceived(const meshtastic_MeshPacket &mp
                        HAS_GPS) {
                 // Decode the Payload some more
                 meshtastic_Position scratch;
-                meshtastic_Position *decoded = NULL;
                 if (mp.which_payload_variant == meshtastic_MeshPacket_decoded_tag && mp.decoded.portnum == ourPortNum) {
                     memset(&scratch, 0, sizeof(scratch));
+                    // A payload that fails to decode leaves nothing to report, so say nothing.
                     if (pb_decode_from_bytes(p.payload.bytes, p.payload.size, &meshtastic_Position_msg, &scratch)) {
-                        decoded = &scratch;
-                    }
-                    // send position packet as WPL to the serial port
-                    {
-                        meshtastic_NodeInfoLite *senderNode = nodeDB->getMeshNode(getFrom(&mp));
+                        // send position packet as WPL to the serial port
+                        const meshtastic_NodeInfoLite *senderNode = nodeDB->getMeshNode(getFrom(&mp));
                         const char *senderName = senderNode ? senderNode->long_name : "";
-                        printWPL(outbuf, sizeof(outbuf), *decoded, senderName,
+                        printWPL(outbuf, sizeof(outbuf), scratch, senderName,
                                  moduleConfig.serial.mode == meshtastic_ModuleConfig_SerialConfig_Serial_Mode_CALTOPO);
                         serialPrint->printf("%s", outbuf);
                     }

suppressions.txt

@@ -52,13 +52,8 @@ postfixOperator:*/mqtt/*
 missingOverride
 virtualCallInConstructor
 
-passedByValue:*/RedirectablePrint.h
-
 internalAstError:*/CrossPlatformCryptoEngine.cpp
 uninitMemberVar:*/AudioThread.h
-// False positive
-constVariableReference:*/Channels.cpp
-constParameterPointer:*/unishox2.c
 
 // False positive: make_zeroizing_array() returns unique_ptr<uint8_t[], ...>, so
 // .get() is uint8_t*, not void*. cppcheck can't resolve the custom-deleter alias
@@ -67,4 +62,41 @@ arithOperationsOnVoidPointer:*/EncryptedStorage.cpp
 
 useStlAlgorithm
 
-variableScope
+variableScope
+
+// cppcheck 2.20 (ESP32 only)
+//
+// The ESP32 CI images build on the pioarduino core, whose esp32 platform installs its own
+// tool-cppcheck 2.20.1 and reinstalls it over any pinned version. Every other platform still
+// resolves platformio/tool-cppcheck 1.21100.230717, i.e. cppcheck 2.11. 2.20 parses far more of
+// this tree than 2.11 managed to, so checks that have always been enabled started firing for the
+// first time - 388 defects on ESP32, none anywhere else, for identical source.
+//
+// Silence the checks that appeared with that jump so the gate means the same thing on every
+// platform again. These are style and performance suggestions, not defects; burning them down is
+// worth doing deliberately, not under a CI outage.
+functionStatic
+staticFunction
+constParameterPointer
+iterateByValue
+returnByReference
+passedByValue
+uselessOverride
+
+constVariable
+constVariablePointer
+constVariableReference
+constParameterReference
+
+// Single deliberate sites, scoped so a new one elsewhere still fails the gate. Router folds the
+// bitfield's want_response bit into the decoded bool; Power interpolates the OCV curve in float.
+bitwiseOnBoolean:*/Router.cpp
+suspiciousFloatingPointCast:*/Power.cpp
+
+// The 2.20 successor to cstyleCast, which is already suppressed above for the same reason.
+dangerousTypeCast
+
+// Sensor drivers hold a driver object they new in begin() and are constructed once, at global
+// scope. cppcheck wants the rule of three on them; nothing ever copies one.
+noCopyConstructor:*/Telemetry/Sensor/*
+noOperatorEq:*/Telemetry/Sensor/*