zeph-core rustdoc gate broken: unresolved [TaskSupervisor::snapshot] intra-doc link in provider_factory.rs

[bug-ops]

Description

The rustdoc gate for zeph-core currently fails on origin/main:

RUSTDOCFLAGS="--deny rustdoc::broken_intra_doc_links" cargo doc --no-deps -p zeph-core \
  --features "candle,classifiers,cocoon,index,metal,mock,profiling,scheduler,sqlite,sysinfo"

fails with an unresolved [TaskSupervisor::snapshot] intra-doc link plus two private_intra_doc_links warnings, all in crates/zeph-core/src/provider_factory.rs:651-653.

Confirmed pre-existing and unrelated to any recent change — git show origin/main:crates/zeph-core/src/provider_factory.rs shows the exact same doc comment text already present on main, unmodified by PR #6328. Found during that PR's review (comment thread, 2026-07-16); filing separately per this project's fast-follow convention since PR #6328 doesn't touch this file.

Reproduction Steps

1. On origin/main, run:

   RUSTDOCFLAGS="--deny rustdoc::broken_intra_doc_links" cargo doc --no-deps -p zeph-core \
     --features "candle,classifiers,cocoon,index,metal,mock,profiling,scheduler,sqlite,sysinfo"
   

2. Observe the build fails on crates/zeph-core/src/provider_factory.rs:651-653.

Expected Behavior

The rustdoc gate (mandatory per .claude/rules/branching.md "Before Every Commit") passes cleanly on main.

Actual Behavior

Gate fails, meaning every PR that runs this check as part of its own commit gate currently gets a false-positive-looking failure unrelated to their own change, until this is fixed.

Environment

• Version/commit: origin/main as of 2026-07-16 (confirmed on commit prior to PR fix(core): wire real turn_tool_calls counter and collapse delegate boilerplate #6328 merge)
• Features: candle,classifiers,cocoon,index,metal,mock,profiling,scheduler,sqlite,sysinfo

Logs / Evidence

Either fix the [TaskSupervisor::snapshot] intra-doc link target in provider_factory.rs:651-653 (method may have been renamed/removed) or adjust the doc comment to reference the correct path, and resolve the two private_intra_doc_links warnings alongside it.