fix(pdf): keep model_path behind the ml feature gate

The model-inventory insertion landed between model_path's #[cfg(feature =
"ml")] attribute and the function it guarded, so the pdf-text (wasm) build
started compiling model_path — which calls the ml-gated prefer_fp32 /
resolve_asset — and CI's wasm32 job failed with E0425. Re-attach the gate
(and the doc comment) to the function itself.

Verified with CI's exact command: cargo check -p docling
--no-default-features --features pdf-text --target wasm32-unknown-unknown
--locked, plus the bare no-default-features wasm check, docling-wasm, the
docling-pdf/serve suites, fmt and clippy.

Signed-off-by: artiz <artem.kustikov@gmail.com>
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01EY5KAiquN4YpVf2PXEQkVT

Author: artiz

crates/docling-pdf/src/lib.rs

@@ -232,12 +232,6 @@ pub(crate) fn resolve_asset(rel: &str) -> String {
     rel.to_string()
 }
 
-#[cfg(feature = "ml")]
-/// Resolve a model path: an explicit env override always wins; otherwise the
-/// INT8 variant of the default path when it exists on disk (the quantized
-/// models are conformance-validated — see docs/PDF_CONFORMANCE.md — and load/run
-/// markedly faster on CPU), unless `DOCLING_RS_FP32` opts back into full
-/// precision; else the fp32 default.
 /// One resolved runtime asset — which file a stage would load right now,
 /// given the CWD, the env overrides and the int8/fp32 preference.
 #[cfg(feature = "ml")]
@@ -296,6 +290,12 @@ pub fn model_inventory() -> Vec<ModelEntry> {
     ]
 }
 
+/// Resolve a model path: an explicit env override always wins; otherwise the
+/// INT8 variant of the default path when it exists on disk (the quantized
+/// models are conformance-validated — see docs/PDF_CONFORMANCE.md — and load/run
+/// markedly faster on CPU), unless `DOCLING_RS_FP32` opts back into full
+/// precision; else the fp32 default.
+#[cfg(feature = "ml")]
 pub(crate) fn model_path(env: &str, fp32_default: &str, int8_default: &str) -> String {
     if let Ok(p) = std::env::var(env) {
         return p;