TypeSchema: terminate package dependency walk on cyclic deps

[ryukzak]

Problem

mkPackageAwareResolver (in src/typeschema/register.ts) walks each package's dependency tree recursively, memoizing the built index into acc[pkgId] only after recursing into dependencies. With mutually-dependent FHIR packages — e.g. hl7.terminology.r5 ↔ hl7.fhir.uv.extensions.r5 (pulled in transitively by the SQL-on-FHIR R5 closure) — the early-return guard (if (acc[pkgId]) return acc[pkgId];) never fires during the cycle, so resolution recurses forever, growing memory until the process is OOM-killed.

Fix

• Memoize acc[pkgId] = index; before recursing into dependencies, so a cyclic dependency terminates at the guard instead of recursing forever.
• Remove the now-redundant post-recursion assignment.

const index = mkEmptyPkgIndex(pkg);
acc[pkgId] = index; // memoize before recursing — cycle terminates at the guard
for (const resource of await manager.search({ package: pkg })) {
    ...
}

Memory consumption

Measured with /usr/bin/time -l bun test test/api/write-generator/multi-package/sql-on-fhir.test.ts (the multi-package test whose R5 closure contains the cyclic packages):

	peak RSS	wall time	outcome
before (cyclic recursion)	~7.2 GB and climbing	never finishes (killed at 150 s)	runaway — OOM
after (this fix)	~1.27 GB	~1.6 s	dependency walk completes

The dependency walk now terminates and the resolver is built in bounded memory. (The SQL-on-FHIR test still reports assertion failures, but on a pre-existing, unrelated issue — Base resource not found 'http://hl7.org/fhir/StructureDefinition/Library' in the org.sql-on-fhir.ig#2.1.0-pre closure — which reproduces identically on published releases and is out of scope here.)

Test

• Adds a regression test driving registerFromManager with a mock manager whose packages form an a ↔ b cycle. A cap on manager.search() calls plus an exact "each package scanned once" assertion make a reintroduced bug fail fast and red instead of slowly exhausting memory. Verified: passes with the fix, fails immediately without it.