Fix Trac 6028: normalize SDCC assembly before preprocessing

[KiritoYG]

Addresses the remaining SDCC examples in Trac 6028. @dptr operands currently cause a syntax error, and #(s_XINIT >> 8) is altered during preprocessing before the late assembler simplifier runs, leaving an unmatched ).

Normalize complete literal __asm / __endasm regions in the raw preprocessor tokens, including newly loaded headers. Preserve an opaque asm() analysis barrier, exactly one terminator and the locations of surrounding C code. Leave ambiguous/missing/nested regions, real preprocessing directives, macro definitions and other assembler dialects on the existing path. The existing pragma-asm handling is unchanged.

Add seven preprocessor test methods covering operands, empty/adjacent blocks, comments, missing/nested markers, other dialects, configurations and unbraced control flow. Two CLI regressions cover the main-file and included-header paths and verify that a real division-by-zero diagnostic after the block remains at its original line.

Validation:

• The untouched base reproduces the remaining @ and #( failures; 18 original/patched CLI comparisons pass, including outside-C diagnostic and GNU/MS/macro controls.
• Windows Clang/MinGW: 5,301 native tests, 351 existing TODOs, zero test failures; both new CLI tests pass.
• Independent Linux GCC 11.4 verification of the exact source: warnings-as-errors build; 5,363 native tests, 360 existing TODOs, zero failures; both CLI tests pass. The helper branch adds only its verification workflow.
• Uncrustify 0.80.1, Python lint and git diff --check pass.

One earlier Windows full-suite attempt exited with 0xc0000005 while displaying TestType::checkTooBigShift_Unix32; the full rerun above passed. The recorded fault offset resolves to the unchanged Token::Match. A bounded debugger run did not reproduce that failure but was stopped after becoming slow in TestValueFlow::valueFlowHang; its outcome is inconclusive. No root cause or baseline attribution is claimed.

This is a bounded fix for the demonstrated literal marker-delimited blocks. It does not repair initial lexer errors, macro-generated markers, or ARM assembler-function syntax.

Please assign Trac 6028 to KiritoYG for this patch and confirm whether this remaining-defect fix qualifies under the published USD 10 bounty bracket. After qualifying closure, I can use the documented bounty-request process; please also confirm the available settlement channel.