[release/2026930][Backport #40705] [NPU] Fix MoE none EP routing and draft backend inheritance - #1308

Backport sgl-project#40705 to Ascend/sglang release/2026930 (base 282d4bbf2b).

The upstream diff applies without release-specific changes. Includes local EP routing, finalize mode 3, draft backend inheritance, documentation and regression tests.

Validation on this backport:

• Python AST syntax, Ruff F401/F821/UP037 checks, and isort checks passed for all changed Python files.
• Ruff formatting checked; the adapted [NPU] Add opt-in MLA prefix FIA and Gemma norm fallback sgl-project/sglang#40131 test was formatted.
• Git diff whitespace checks passed.
• All four backports merge together without conflicts.
• Windows cannot run the complete runtime test suite because the Linux resource module is unavailable. NPU accuracy/performance tests were not rerun; upstream hardware results are historical, not release-branch validation.