docs: add package-local AI guidance

[linkdata]

Summary

• add an indexed AI.md guide beside each of the 16 Go packages in the module
• keep READMEs focused on human onboarding while retaining unusual caller-facing concepts in package Godoc, including tags, widget identity and multiplicity, trust boundaries, build-dependent loading, and wire framing
• route version-matched agent guidance through the adjacent package guide while keeping the installed JaWS skill self-contained
• repair moved references and review-sensitive details for request routes, JsVar paths, transport limits, protocol parsing, Bootstrap synchronization, and the repository test matrix

This is a documentation-only change with no runtime behavior or public API changes.

Verification

• go generate ./...
• gofmt -l .
• gofumpt -l .
• go vet ./...
• staticcheck ./...
• golangci-lint run
• gosec ./...
• go build ./...
• JAWS_REQUIRE_NODE=1 go test -race ./...
• JAWS_REQUIRE_NODE=1 go test ./...
• GOARCH=386 CGO_ENABLED=0 go test ./lib/bind/... ./lib/ui/... (build-386 CI job)
• rendered go doc review for every changed package synopsis and exported comment
• case-sensitive package-guide completeness, local Markdown link/fragment, and stale-reference checks