Normalized the AI disclosure comment to one fixed line per file (#740)

The per-edit disclosure named the product and model, so every agent and every
model version appended another line. 74 files carried two to four of them, and
the same five products had accumulated 13 spellings -- Copilot against GitHub
Copilot, Claude Sonnet 4.6 against claude-sonnet-4.6, four spellings of Codex.
Twenty assembly lines carried a doubled comment marker, `; //` or `@ //`.

Every file now carries exactly one line, fixed text naming no product:

    Portions of this file were generated with AI assistance.

It is written with the comment character that file already uses, so the `;`
and `@` assembly files keep theirs and the doubled markers are gone. Precise
attribution stays on the commit, where the Assisted-by trailer is per-change,
dated and attached to the diff it describes. A header line cannot hold that
record honestly, because the code it names gets rewritten and the line stays.
A file-level flag answers whether; the history answers who.

Comment-only. 455 files, 455 insertions and 574 deletions: every removed line
was a disclosure line, every added line is the fixed text, and no file is left
with zero or with more than one. `scripts/check_ports.sh` passes, including the
reproducibility check that would catch a ports_arch master and its generated
copies drifting apart. Recompiled against dev, every file that builds without a
vendor toolchain gives a byte-identical object: 19 of 19 C files under common,
100 of 100 GNU assembly files, and all 16 assemblable files whose comment
marker changed. The 10 remaining marker changes are ac5 and IAR sources where
`;` already started the comment and only the redundant `//` was removed.

Assisted-by: Claude Code (Opus 5) <noreply@anthropic.com>

test/smp/regression/testcontrol.c

@@ -10,9 +10,7 @@
 /***************************************************************************/
 
 /* This is the test control routine of the ThreadX kernel.  All tests are dispatched from this routine.  */
-// Some portions generated by Codex (gpt 5.5).
-// Some portions generated by Copilot (Opus 5).
-// Some portions generated by Codex (gpt-5.6-sol).
+// Portions of this file were generated with AI assistance.
 
 #define TX_THREAD_SMP_SOURCE_CODE
 

test/smp/regression/threadx_block_memory_suspension_timeout_test.c

@@ -11,7 +11,7 @@
 
 /* This test is designed to test timeouts on suspension on memory block pools.  */
 
-// Some portions generated by Codex (gpt 5.4).
+// Portions of this file were generated with AI assistance.
 
 #include   <stdio.h>
 #include   "tx_api.h"

test/smp/regression/threadx_byte_memory_suspension_timeout_test.c

@@ -11,7 +11,7 @@
 
 /* This test is designed to test suspension timeout on a memory byte pool.  */
 
-// Some portions generated by Codex (gpt 5.4).
+// Portions of this file were generated with AI assistance.
 
 #include   <stdio.h>
 #include   "tx_api.h"

test/smp/regression/threadx_smp_random_resume_suspend_exclusion_pt_test.c

@@ -10,7 +10,7 @@
 /***************************************************************************/
 
 /* Define the ThreadX SMP random resume/suspend/exclude/pt test.  */
-// Some portions generated by Codex (gpt 5.4).
+// Portions of this file were generated with AI assistance.
 
 #include   <stdio.h>
 #include   "tx_api.h"

test/smp/regression/threadx_smp_time_slice_test.c

@@ -11,7 +11,7 @@
 
 /* Define the ThreadX SMP time-slice test.  */
 
-// Some portions generated by Codex (gpt 5.4).
+// Portions of this file were generated with AI assistance.
 
 #include   <stdio.h>
 #include   "tx_api.h"

test/smp/regression/threadx_thread_multiple_sleep_test.c

@@ -11,7 +11,7 @@
 
 /* This test is designed to test multiple threads sleeping for 33 ticks.  */
 
-// Some portions generated by Codex (gpt 5.4).
+// Portions of this file were generated with AI assistance.
 
 #include   <stdio.h>
 #include   "tx_api.h"

test/smp/regression/threadx_thread_stack_checking_test.c

@@ -9,7 +9,7 @@
 /* SPDX-License-Identifier: MIT                                            */
 /***************************************************************************/
 
-// Some portions generated by Copilot (Opus 5).
+// Portions of this file were generated with AI assistance.
 
 /* This test is for the thread stack checking services.  */
 

test/smp/regression/threadx_thread_stack_fill_value_test.c

@@ -8,7 +8,7 @@
 /* SPDX-License-Identifier: MIT                                            */
 /***************************************************************************/
 
-// Some portions generated by Copilot (Opus 5).
+// Portions of this file were generated with AI assistance.
 
 /* This test checks that the stack fill value recorded in a thread control block is the
    value that was actually written into that thread's stack.  The two used to disagree

test/tx/cmake/riscv/bsp/tx_initialize_low_level.S

@@ -9,7 +9,7 @@
  * SPDX-License-Identifier: MIT
  **************************************************************************/
 
-// Some portions generated by Claude Code (Opus 5).
+// Portions of this file were generated with AI assistance.
 
 /* Trap entry and low-level init for RISC-V QEMU virt regression tests.
    Supports both RV32 and RV64 via __riscv_xlen conditionals. */

test/tx/regression/testcontrol.c

@@ -10,8 +10,7 @@
 /***************************************************************************/
 
 /* This is the test control routine of the ThreadX kernel.  All tests are dispatched from this routine.  */
-// Some portions generated by Codex (gpt 5.4).
-// Some portions generated by Copilot (Opus 5).
+// Portions of this file were generated with AI assistance.
 
 #include "tx_api.h"
 #include <stdio.h>

test/tx/regression/threadx_initialize_kernel_setup_test.c

@@ -10,7 +10,7 @@
 /***************************************************************************/
 
 /* This test is designed to test kernel setup functionality in ThreadX.  */
-// Some portions generated by Codex (gpt 5.4).
+// Portions of this file were generated with AI assistance.
 
 #include   <stdio.h>
 #include   <stdlib.h>

test/tx/regression/threadx_thread_basic_execution_test.c

@@ -1,6 +1,6 @@
 /***************************************************************************/
 
-/* Some portions generated by Codex (gpt-5.6-sol). */
+// Portions of this file were generated with AI assistance.
 /* Copyright (c) 2024 Microsoft Corporation                                */
 /* Copyright (c) 2026 Eclipse ThreadX contributors                         */
 /*                                                                         */

test/tx/regression/threadx_thread_stack_checking_test.c

@@ -9,7 +9,7 @@
 /* SPDX-License-Identifier: MIT                                            */
 /***************************************************************************/
 
-// Some portions generated by Copilot (Opus 5).
+// Portions of this file were generated with AI assistance.
 
 /* This test is for the thread stack checking services.  */
 

test/tx/regression/threadx_thread_stack_fill_value_test.c

@@ -8,7 +8,7 @@
 /* SPDX-License-Identifier: MIT                                            */
 /***************************************************************************/
 
-// Some portions generated by Copilot (Opus 5).
+// Portions of this file were generated with AI assistance.
 
 /* This test checks that the stack fill value recorded in a thread control block is the
    value that was actually written into that thread's stack.  The two used to disagree

test/tx/regression/threadx_trace_entry_update_test.c

@@ -12,7 +12,7 @@
  *
  * SPDX-License-Identifier: MIT and CC0-1.0
  **************************************************************************/
-// Some portions generated by Codex (gpt-5.6-sol).
+// Portions of this file were generated with AI assistance.
 
 /* This test drives the trace entry update paths -- the blocks guarded by
    TX_ENABLE_EVENT_TRACE that go back and patch a trace entry after the call