feat(patterns): add core pattern registry

[ofabiodev]

Summary

Adds the internal v0.1 pattern registry and resolves the initial core effects and events required by the compiler pipeline.

Changes

• Add registration and resolution for effect, expression, condition, and event patterns
• Add core support for send ... to ..., on load, and on tick
• Add documented unknown and ambiguous pattern diagnostics
• Preserve named token captures and source spans for future IR lowering
• Reject duplicate, adjacent, and ambiguously matched placeholders

Testing

make test
cd src
go test ./... -count=1
go vet ./...
go test ./internal/patterns -shuffle=on -count=50
go test ./internal/patterns -cover