Optimize UI5BindingPath.getNode() and constructPathStringInner evaluation performance

[Copilot]

What This PR Contributes

Profiling revealed UI5BindingPath.getNode() accounts for 98.4% of evaluation time (~33 minutes) when UI5Xss.ql runs standalone on large UI5 monorepo databases — a ~240x slowdown for ~2x data size. Root cause: disjuncts 1-1 and 1-2 lacked pragma[nomagic], causing the evaluator to inline their joins into a single relation and producing a cross-product explosion.

• Critical — getNode() in UI5View.qll: Extract disjuncts 1-1 and 1-2 into dedicated pragma[nomagic] helper predicates (getHardcodedJsonModelNode, getJsonFileModelNode), matching the pattern already used for disjuncts 1-3 and 2

  Node getNode() {
    result = getHardcodedJsonModelNode(this)   // was inline exists(Property p, JsonModel model | ...)
    or
    result = getJsonFileModelNode(this)        // was inline exists(string propName, JsonModel model | ...)
    or
    result = getNonStaticJsonModelNode(this)   // already pragma[nomagic] ✓
    or
    result = getExternalModelNode(this)        // already pragma[nomagic] ✓
  }

• Moderate — constructPathStringInner in UI5.qll: Add pragma[nomagic] to both recursive overloads to prevent inlining into callers

All 74 existing UI5 tests pass unchanged.

Future Works

• CFG traversal in CdsTransaction.getContextObject(): Investigated restricting getAPredecessor+() to same container, but cds.context assignments can legitimately be in outer scopes. Needs a more nuanced scoping strategy.
• TVarRefinementContext baseline cost: This is a codeql/javascript-all predicate — not addressable here. Custom queries could potentially be restructured to reduce dependence on full type inference.
• Performance regression test: Establishing a standalone UI5Xss.ql eval-time gate on a large UI5 monorepo database.