Fix documentation build warnings and HTML size error

- Double HTML size thresholds to 2 MB (manual-plot.md was 1.32 MiB)
- Qualify constraint/objective/variable/discretize in public.md @docs block
- Use qualified @ref for variable/objective in manual files
- Add @id anchor to Solver requirements section in manual-solve.md
- Fix @ref to use new anchor in manual-solve-gpu.md
- Restrict methods() entry to avoid Base.methods docstring leak

Resolves CI-blocking HTMLSizeThresholdError and eliminates local
undefined binding warnings. Remaining @ref warnings require fixes
in upstream packages (CTModels, CTSolvers, CTFlows).

Author: ocots

docs/src/api/public.md

@@ -41,6 +41,7 @@ boundary_constraints_dual
 boundary_constraints_nl
 bypass
 components
+CTModels.OCP.constraint
 constraints
 constraints_violation
 control
@@ -65,7 +66,7 @@ dim_path_constraints_nl
 dim_state_constraints_box
 dim_variable_constraints_box
 dimension
-discretize
+CTDirect.discretize
 dual
 dynamics
 export_ocp_solution
@@ -111,10 +112,11 @@ lagrange
 mayer
 message
 metadata
-methods
+methods()
 model
 name
 nlp_model
+CTModels.OCP.objective
 ocp_model
 ocp_solution
 option_default
@@ -147,6 +149,7 @@ time
 time_grid
 time_name
 times
+CTModels.OCP.variable
 variable_components
 variable_constraints_box
 variable_constraints_lb_dual

docs/src/manual-initial-guess.md

@@ -565,7 +565,7 @@ nothing # hide
 
 !!! tip "Interactions with an optimal control solution"
 
-    Please check [`state`](@ref), [`costate`](@ref), [`control`](@ref) and `variable` to get data from the solution. The functions `state`, `costate` and `control` return functions of time and `variable` returns a vector.
+    Please check [`state`](@ref), [`costate`](@ref), [`control`](@ref) and [`variable`](@ref CTModels.OCP.variable) to get data from the solution. The functions `state`, `costate` and `control` return functions of time and `variable` returns a vector.
 
 ## Costate / multipliers
 

docs/src/manual-model.md

@@ -101,9 +101,9 @@ Each field can be accessed directly (`ocp.times`, etc) or by a getter:
 * [`times`](@ref)
 * [`state`](@ref)
 * [`control`](@ref)
-* `variable`
+* [`variable`](@ref CTModels.OCP.variable)
 * [`dynamics`](@ref)
-* `objective`
+* [`objective`](@ref CTModels.OCP.objective)
 * [`constraints`](@ref)
 * [`definition`](@ref)
 

docs/src/manual-plot.md

@@ -208,7 +208,7 @@ The previous solution of the optimal control problem was obtained using the [`so
 
 !!! tip "Interactions with an optimal control solution"
 
-    Please check [`state`](@ref), [`costate`](@ref), [`control`](@ref), and `variable` to retrieve data from the solution. The functions `state`, `costate`, and `control` return functions of time, while `variable` returns a vector.
+    Please check [`state`](@ref), [`costate`](@ref), [`control`](@ref), and [`variable`](@ref CTModels.OCP.variable) to retrieve data from the solution. The functions `state`, `costate`, and `control` return functions of time, while `variable` returns a vector.
 
 ```@example main
 using OrdinaryDiffEq