[codex] update overlap docs example and local resolve note

[terasakisatoshi]

Summary

• update the public overlap examples in the README and guide to use the current overlap(basis.v, ρ₀) form
• add a short development note explaining that Pkg.resolve() can recover from a stale local Manifest.toml
• keep the PR scope limited to the three requested documentation files

Why

The main public example still used an obsolete broadcasted overlap.(basis.v, ρ₀) call, which no longer matches the current API and was reported in issue #136. While investigating that report, the local development flow also benefited from a short note about recovering from out-of-sync local manifests.

Fixes #136.

Validation

• JULIA_DEPOT_PATH=$PWD/.codex-julia-depot julia --project=.tmp/test-feature-env -e 'using Test; readme=read("README.md", String); guide=read(joinpath("docs","src","guide.md"), String); @test !occursin("overlap.(basis.v, ρ₀)", readme); @test !occursin("overlap.(basis.v, ρ₀)", guide); @test occursin("overlap(basis.v, ρ₀)", readme); @test occursin("overlap(basis.v, ρ₀)", guide); dev=read("development.md", String); @test occursin("Pkg.resolve()", dev); println("DOCS_VERIFY_OK")'
• JULIA_DEPOT_PATH=$PWD/.codex-julia-depot julia --project=.tmp/test-feature-env .tmp/test-feature/core_workflow.jl
• JULIA_DEPOT_PATH=$PWD/.codex-julia-depot julia --project=.tmp/test-feature-env -e 'using Pkg; Pkg.test("SparseIR")'