feat(xlang): heuristic HTTP linker v1 (TS fetch/axios <-> Java/Python routes)

[rahlk]

Heuristic HTTP linker v1: match consumes-facts to provides-facts across projects — TypeScript fetch/axios calls ↔ Java/Python routes.

Scope

• Route-template unification: path params, prefixes, base URLs from config where cheap.
• Emits canonical boundary edges; every match carries its evidence and is structural.
• Precision over recall: an unmatched consume is surfaced as unresolved, never silently dropped.

Part of #196. Branch: feat/issue-<n>.