fix(schema): admit L4's compound body-node ids so an -a 4 payload validates

[rahlk]

Problem

localId in src/test/resources/schema/analysis.v2.schema.json was written before L4 and admitted only a bare line:col or an @-tagged synthetic vertex. SdgVertices keys a call site's actuals off the site's own local id — <line:col>/actual_in:<i> and <line:col>/actual_out — so none of them matched.

An -a 4 document therefore failed this repository's own conformance gate. Measured on the daytrader8 fixture: 2936 validation errors, every one of them these two forms (1943 × N:N/actual_in:N, 993 × N:N/actual_out) and nothing else.

Surfaced while running the release gates for 3.0.0 — the release that introduces L4.

Fix

The pattern now enumerates the two compound forms rather than loosening its character class, per the issue's caveat that a pattern relaxed to accept anything containing a slash would gate nothing:

^(\d+:\d+(/actual_in:\d+|/actual_out)?|@[A-Za-z0-9_:.$/-]+)$

Still rejected: an actual_in missing its ordinal, an actual_out carrying one, an unknown suffix, a base that is not a position, and a bare trailing slash.

The emitted ids were correct throughout — only the schema describing them was stale. No id changes, no graph-projection changes, no revisiting of the id grammar.

Answering the issue's open question

The issue flagged that the gate "has apparently only ever run at L1, so its coverage of L2 and L3 ids is also unproven." Checked directly: -a 1, -a 2 and -a 3 documents all validate clean against the unmodified schema. L4 was the only gap.

Tests

• L4GateTest.theLevel4DocumentValidatesAgainstTheV2Schema — validates the real -a 4 document the test already builds from the l4-sdg-test fixture. Fails before this change, passes after.
• L4SchemaOracleTest — 9 hand-authored cases: the two compound forms and the pre-existing forms accepted, five malformed shapes rejected.

Suite: 487 tests, 1 failure, 4 skips — the failure is the pre-existing Docker-dependent CodeAnalyzerIntegrationTest > initializationError, unrelated and unchanged.

Closes #207