Refactor static schema parser into phase pipeline (#3027)
* test: cover run-first schema parser targets
* refactor: add schema parser phase state
* refactor: route schema parser through phases
* refactor: make run the primary schema target
* refactor: cache schema parser module loading
* test: cover schema parser phase boundaries
* refactor: split schema parser helpers by responsibility
* refactor: finish schema parser input split
* refactor: avoid parser phase builtin shadow
* docs: document schema parser phase pipeline
* refactor: clean up schema parser boundaries
* fix: prefer standalone run target in schema parser
* docs: clarify schema target resolution
* fix: resolve parser review edge cases
* fix: remove unused parser fields
* test: add focused schema parser coverage
* Clarify streaming parser error
* refactor: move streaming annotation parsing
* fix: appease streaming decorator staticcheck
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Co-authored-by: copilot-swe-agent[bot] <198982749+Copilot@users.noreply.github.com>
