Fix docs build for Documenter 1.17 (compat bump #139 follow-up)

[ChrisRackauckas-Claude]

Please ignore until reviewed by @ChrisRackauckas.

This supersedes / builds on the Dependabot compat bump in #139
(dependabot/julia/docs/all-julia-packages-27dc8c0b02). It carries the same
compat bumps (Documenter 1.17, Flux, Plots, Distributions, NLSolversBase,
Revise, MLDatasets, StableRNGs, PyCall, SymPy, IJulia across docs/ and
examples/) and adds the code/docs changes needed to make the docs build pass
under Documenter 1.17. Opened from a fork because ChrisRackauckas-Claude only
has triage/pull (not push) on the SciML repo.

(A) Documenter 1.17 docs-build fixes

Documenter 1.17 promotes two doc-check categories from warnings to hard errors.
Reproduced locally (julia +1.11, Documenter 1.17.0) — the unmodified bump
branch failed with:

┌ Error: 12 docstrings not included in the manual:
│     Evolutionary.psin, Base.rand(::AbstractRNG, ::TreeGP), Evolutionary.plog,
│     Evolutionary.psqrt, Evolutionary.cond, Evolutionary.pexp, Evolutionary.pdiv,
│     Evolutionary.genop, Evolutionary.pcos, Evolutionary.ppow,
│     Evolutionary.nop(::AbstractStrategy), Evolutionary.aq
┌ Error: unused footnote named '1'..'9' in docs/src/mutation.md.
┌ Error: unused footnote named '1'..'3' in docs/src/selection.md.
┌ Error: unused footnote named '1'..'7' in docs/src/crossover.md.
ERROR: LoadError: `makedocs` encountered errors [:footnote, :missing_docs]

Fix 1 — 12 missing docstrings

The GP protected operators (pdiv, aq, pexp, plog, psqrt, psin, pcos, ppow, cond), Base.rand(::AbstractRNG, ::TreeGP), the no-op genop(recombinant) GA
operator and the strategy nop(::AbstractStrategy) operator had docstrings but
were never referenced by any @docs/@autodocs block. Added:

• docs/src/gp.md: a "Protected Functions" @docs block plus
  Base.rand(::AbstractRNG, ::TreeGP) (under a CurrentModule = Evolutionary
@meta block).
• docs/src/mutation.md: Evolutionary.genop(recombinant) and
  Evolutionary.nop(::AbstractStrategy).

Fix 2 — "unused footnote" errors

The footnote references ([^N]) live inside the docstrings that are spliced
into mutation.md / selection.md / crossover.md via @docs blocks, but the
footnote definitions ([^N]:) lived in the page body under a ## References
heading. Documenter 1.17 scopes docstring footnotes separately from page-body
footnotes, so every body definition looked orphaned (verified with a minimal
reproduction: ref-in-docstring + def-in-body errors; ref+def both in
docstrings, including across two docstrings on the same page, passes).

Fix: moved each footnote definition into a # References section of the
docstring(s) that reference it (src/mutations.jl, src/recombinations.jl,
src/selections.jl); one definition per id per page is shared across all
docstrings on that page. The genuinely stale crossover.md [^1] (Mühlenbein
1993, referenced by no docstring) was removed. The bibliographies still render
(now inside the docstrings) — nothing was silenced; warnonly/doctest=:none
were not used.

Local docs-build evidence (after fix)

[ Info: SetupBuildDirectory ... Doctest: skipped.
[ Info: ExpandTemplates ... CrossReferences ... CheckDocument: running document checks.
[ Info: Populate ... RenderDocument ... HTMLWriter: rendering HTML pages.
┌ Warning: Documenter could not auto-detect the building environment. Skipping deployment.
EXIT: 0

Zero errors. Confirmed the rendered HTML contains the new docstrings and the
footnote bibliographies (gp/index.html has all 9 protected fns; mutation /
crossover / selection retain their references).

(B) The ubuntu Julia "1" / "pre" "test failure" is a Codecov upload flake, not a test failure

The root Project.toml is unchanged by this bump (only docs/Project.toml
and examples/Project.toml changed), and the package test target only depends
on Test + StableRNGs. So the bump cannot affect the package test
environment.

Looking at the actual CI job steps for run 26918986336:

Job	Run tests step	Report Coverage with Codecov step	Overall
ubuntu 1	pass	FAIL "Server failed to authenticate the request" -> exit 255	FAIL
ubuntu pre	pass	FAIL "Server failed to authenticate the request" -> exit 255	FAIL
ubuntu lts	pass	pass	pass
windows 1	pass	pass	pass

The test step itself passed on every job, including the two "failing" ones.
The X is on the Codecov upload step, which hit a transient Codecov auth error
(Server failed to authenticate the request. Make sure the value of Authorization header is formed correctly including the signature) and exited
255. The same auth annotation shows up on other jobs too; lts (also ubuntu,
also ~1h14m) had the identical test step pass and Codecov succeed. The ~1h job
duration is just the coverage-instrumented run time (lts took 1h14m and
passed), not a hang.

This is a transient Codecov infrastructure flake — not caused by the bump and
not a test regression. A re-run should clear it.

Local test evidence (julia +1.11)

• This branch: Testing Evolutionary tests passed, exit 0, ~219s
  (all testsets pass: n-Queens, Knapsack, OneMax, Multi-objective EA,
  Regression, Genetic Programming).
• Clean master: Testing Evolutionary tests passed, exit 0 — identical,
  confirming no pre-existing test failure and no bump-induced regression.

(Local runs are faster than CI because CI runs with coverage instrumentation.)

Formatting

Runic v1 (1.7.0) reports 0 files need reformatting across src/, test/,
and docs/make.jl.

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