Make the AST node catalog reflection-free

[nickna]

Summary

• preserve the public AstNodeCatalog API while replacing nested-type reflection with an explicit canonical type list
• retain automatic completeness and dispatch coverage by deriving the actual node set reflectively in managed tests
• remove all 47 AstNodeCatalog IL3050 publish warnings and ratchet the Linux Native publish baseline from 72 to 25 total warnings (56 to 9 project-owned)
• document the new baseline and measured Native image impact

Validation

• source analyzer baseline: 0 project warnings
• full managed suite: 16,262 passed
• AST dispatch tests: 7 passed
• Windows arm64 Native publish: 9 project warnings; 18 external informational warnings
• Native smoke probes: interpreted output 42; compiled features output 2 2 33
• win-arm64 Native image: 93,374,976 bytes, 1,024 bytes smaller than merged main

Linux CI remains authoritative for the checked-in 25-warning publish baseline (9 project plus 16 external). No warnings are suppressed.