Own build-state retirement policy in CNC

[Zetazzz]

Architecture

This PR keeps the opt-in policy in CNC and the inaccessible Graphile internals in pnpm patches.

CNC normal source

• Adds the independently importable BuildStateRetirementPlugin in graphile-settings.
• The plugin registers build.registerAfterSchemaValidation(...) and is the only component that decides whether and when retirement runs.
• ConstructivePreset explicitly installs the plugin.
• Graphile defaultPreset remains unchanged.

CNC pnpm patches

• Mirrors Crystal PR Server #1 neutral after-schema-validation lifecycle in graphile-build dist.
• Keeps the retirement state machine, core and Behavior cleanup, owner disposer registration/execution, released-state guards, and aggregate disposal errors inside the patch.
• Uses a private symbol capability to let the CNC plugin trigger retirement without exporting a Graphile retirement plugin.
• Keeps PgBasics, PgCodecs, and PgPolymorphism owner cleanup in graphile-build-pg.
• Does not modify pg-many-to-many.

CNC owners

• graphile-search clears its build codec cache.
• graphile-connection-filter clears its operator registry.
• graphile-meta snapshots runtime metadata from the finalized schema.

Contracts

• no CNC plugin: retained state and original behavior
• validation failure: no retirement
• installed plugin: retirement only after successful validation
• disposers: deterministic reverse order; all attempted; failures aggregated
• retirement: fail-closed with GRAPHILE_BUILD_STATE_RELEASED
• executable schemas remain independent of retired build state

Validation

• retirement contract tests: 5 passed
• graphile-search owner test: passed
• connection-filter owner test: passed
• graphile-meta tests: 131 passed, 3 snapshots
• real PostgreSQL ConstructivePreset integration: 38 passed
• graphile-settings/search/connection-filter/meta builds: passed
• ESLint on affected sources: no errors (one pre-existing graphile-search unused-variable warning)
• frozen-lockfile install: passed
• git diff --check: passed

[Zetazzz]

Closing as superseded by #1722 on the replacement stack (#1716 → #1719 → #1722). Build-state retirement architecture and any further boundary changes will continue in #1722. This PR remains available as historical design context.