feat(agama): add literal-handling conformance tests for the transpiler

@imran-ishaq is already working on this.

Since Jun 24, 2026.

**Is your feature request related to a problem? Please describe.**
The Agama language reference defines precise rules for literals (strings and escaping, lowercase booleans, base-10
numbers with no exponential notation, null, lists, maps). There is no test asserting the transpiler accepts the valid
forms and rejects the documented invalid number forms, so a regression in literal parsing could go unnoticed.

**Describe the solution you'd like**
Add a test that transpiles a flow using all valid literal forms and confirms it succeeds, plus a negative check that
invalid number forms (1E-05, .1, -.1, +1) are rejected — pinning the transpiler to the language reference. Register it
in the TestNG suite.

**Describe alternatives you've considered**
Relying on the existing malformed-flow tests — rejected: they don't pin the valid literal forms, so accidental
tightening/loosening of literal parsing wouldn't be caught.

**Additional context**
Part of the effort to add semantic/spec-conformance coverage to the Agama subsystem.