docs: fix unresolvable @extref in _strategy_parameter docstring (#943)

CHANGELOG.md

@@ -40,6 +40,8 @@ Dependency realignment onto the released control-toolbox ecosystem, the v2.0 →
 
 - The documentation site was rewritten onto a new sitemap (getting started, modelling, solve, results, flows, geometry, an examples gallery, and a thematic API reference) and a v2.0 → v2.1 migration page added. The retired v2.0 manuals are kept under `docs/attic/`
 
+- **`_strategy_parameter` docstring no longer emits an unresolvable `@extref`** ([#943](https://github.com/control-toolbox/OptimalControl.jl/issues/943)). It cross-referenced `CTBase.Strategies.parameter` by method signature (`parameter(T, default)` / `parameter(T)`), but CTBase's auto-generated reference indexes the function under a single anchor, so neither link resolved. Collapsed to the one anchor; `docs/make.jl`'s `warnonly` comment refreshed. The remaining `@extref` warnings (`Plots.plot(::CTModels.Solutions.Solution)`) are fixed upstream in [CTModels 0.19.4-beta](https://github.com/control-toolbox/CTModels.jl/issues/427).
+
 ### 📦 Dependencies
 
 - **Realigned on the released ecosystem** — every sibling resolves from the General registry with no `Pkg.develop`: CTBase `0.28`→`0.29`, CTModels `0.15`→`0.18`, CTSolvers `0.4`→`0.5`, CTFlows `0.16`→`0.17`, CTParser `0.8`→`0.9`, CTLie `0.1`→`0.2`; CTDirect stays pinned to `1` (the major alone, per the pinning-granularity rule)

docs/make.jl

@@ -263,12 +263,15 @@ with_api_reference(src_dir, ext_dir) do api_pages
     return makedocs(;
         draft=draft,
         remotes=nothing, # Disable remote links. Needed for DocumenterReference
-        # Not fully zero: 2 unresolved @ref (DOCPCache, category :cross_references) and 6
-        # unresolved @extref (CTModels.Solution / CTBase.Strategies.parameter — a *separate*
-        # category, :external_cross_references, registered by DocumenterInterLinks, not
-        # Documenter itself) are upstream defects, tracked at control-toolbox/CTDirect.jl#630,
-        # control-toolbox/CTModels.jl#416 and control-toolbox/CTBase.jl#543 respectively. Drop
-        # this exclusion once those land — see .reports/campaign/D-api-reference.md.
+        # Not fully zero: 2 unresolved @ref remain (DOCPCache, category :cross_references),
+        # tracked at control-toolbox/CTDirect.jl#630 — drop :cross_references once that lands.
+        # The @extref backlog (category :external_cross_references, registered by
+        # DocumenterInterLinks, not Documenter itself) is cleared: the CTBase.Strategies.parameter
+        # links were this repo's own signature-suffixed docstring (#943, fixed here) and the
+        # Plots.plot(::CTModels.Solutions.Solution) links were CTModels' extension docstrings
+        # (control-toolbox/CTModels.jl#427, fixed in CTModels 0.19.4-beta). Once that release is
+        # in docs/Manifest.toml, :external_cross_references can be dropped from this list so a
+        # future unresolved @extref fails the build. See .reports/campaign/D-api-reference.md.
         #
         # :example_block is deliberately *not* here: the one remaining un-expanded @example
         # (CTParser's @def docstring, control-toolbox/CTParser.jl#341, transcluded onto

src/helpers/print.jl

@@ -331,11 +331,10 @@ $(TYPEDSIGNATURES)
 
 Parameter type of a strategy, or `nothing` when it declares none.
 
-Since CTBase 0.28.8-beta this is a thin wrapper around
-[`CTBase.Strategies.parameter(T, default)`](@extref) — the non-throwing counterpart to
-[`CTBase.Strategies.parameter(T)`](@extref) requested as
-[CTBase#518](https://github.com/control-toolbox/CTBase.jl/issues/518), so display no longer
-needs its own `try`/`catch` around `NotImplemented`.
+Since CTBase 0.28.8-beta this is a thin wrapper around the two-argument form of
+[`CTBase.Strategies.parameter`](@extref) — the non-throwing counterpart to its one-argument
+form ([CTBase#518](https://github.com/control-toolbox/CTBase.jl/issues/518)), so display no
+longer needs its own `try`/`catch` around `NotImplemented`.
 
 Display must not be the thing that crashes on a third-party strategy which simply chose not to
 be parameterized. Every in-tree strategy implements the contract, so the fallback path below is