NebGuard: versionet e vjetra dhe historiku

Features
- session usage counts requests by trigger and context band

Bug Fixes
- tests find their files without the build path
- lint skips the golangci Actions cache on a persistent lint cache
- every base image pins its digest
- place a gh pr merge whose message value is a quoted substitution
- stop re-reading every checkout on each pre-tool-use hook
- a seat session shows no dollar cost
- a closed execution intake is not collected again
- savings dollars price from the one list price table
- a compression note names retrieve's arguments
Signed, verifiable artifacts. Verify per the repository README before use.

Bug Fixes
- a downgraded guide says guide
- the home guard reads a repo-relative .nebcore against its folder
- the train gate passes a gitops repository by name
- the train gate reads a remote gitops merge by its named repository
- a private session reads the catalog only by exact filter
- a private session searches the catalog by exact filter
- a generic envelope names no agent run
- an execution's generic envelope names its agent run
Signed, verifiable artifacts. Verify per the repository README before use.

Bug Fixes
- help: make all user-visible output public facing