doc(README): introduce context&templates

fix(path): eulerian path.

chore(path): `path` in local env support `.md ` file

test(chatdev): add the chatdev agent.

fix(role): fix local env, that role path undefined.

test(chatpdf): add examples - chatpdf

release(0.1.5): release update

feat(key): support any key for custom extensions

fix(scheme): node type `scheme` fix

feat(splitter): splitter support more

feat(prompt): prompt support logic-less template syntax.

chore(file): delete `tsc` compiled file

feat(type): add new type support "scheme" | "doc" | "retrieve"

fix(env): local env should build the `doc.path` file to `libs`.

feat(context): New context definition