Recycle type checkers under a configurable memory budget

[Copilot]

Large programs retain substantial checker-owned state, causing memory usage to grow throughout type checking. This change adds opt-in checker recycling for memory-constrained compilation.

Changes

• Adds --maxMemory <MiB> for non-incremental --noEmit compilation.
• Replaces checker-pointer affinity with stable pool slots, allowing checker replacement without reassigning files.
• Recycles checkers between checked files when live heap allocation exceeds the configured budget.
• Preserves retired checkers’ global diagnostics and aggregate symbol, type, and instantiation counts.
• Avoids recycling after skipped files or after a slot’s final checked file.
• Disables recycling where checker-owned state must survive, including declaration emit, tracing, incremental compilation, and watch mode.
• Reports Checkers retired under extended diagnostics.

tsgo -p tsconfig.json --noEmit --checkers 8 --maxMemory 8192

[Daniel Rosenwasser (DanielRosenwasser)]

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