feat(parser): add PUBLISH/SUBSCRIBE/UNSUBSCRIBE and DEFINE EVENT parsing

[LostRhapsody]

Implement full parsing support for ABL's event system:

• Named event statements: PUBLISH, SUBSCRIBE, UNSUBSCRIBE
• Class event declaration: DEFINE EVENT with SIGNATURE VOID(...)
• 7 new keywords via codegen (PUBLISH, SUBSCRIBE, UNSUBSCRIBE, ANYWHERE, EVENT, SIGNATURE, RUN-PROCEDURE)
• Hand-rolled event-name parser to avoid function-call ambiguity
• Shared parse_run_arguments() helper extracted for reuse
• SubscribeTarget enum for required IN/ANYWHERE choice
• 19 new tests covering all syntax variants + disambiguation

[codspeed-hq]

Merging this PR will improve performance by 10.69%

⚠️ Different runtime environments detected

Some benchmarks with significant performance changes were compared across different runtime environments,
which may affect the accuracy of the results.

Open the report in CodSpeed to investigate

⚡ 1 improved benchmark
✅ 14 untouched benchmarks

Performance Changes

	Benchmark	BASE	HEAD	Efficiency
⚡	temp_tables	177.5 µs	160.3 µs	+10.69%

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_{Comparing feat/publish-subscribe (233af8c) with master (ae26e42)}