Re-vendor the shared files from sneak/prompts at 0653579 (closes #52)

Takes .golangci.yml, .dockerignore, .gitignore, .editorconfig, the
workflow and REPO_POLICIES.md from sneak/prompts 0653579, with this
repository's own entries after the shared content. Lint (golangci-lint
v2.14.0) and test are Dockerfile phases that script/lint and script/test
build alone with a new CACHEBUST value, keeping Go's and golangci-lint's
caches; the image build depends on both. make fmt and make fmt-check also
format the markdown with prettier, pinned in yarn.lock. The agent
guidance moves to AGENTS.md. The Go code is fixed for what the new
configuration finds, and the AS and prefix detail reads now return the
rows' error after their loops.

Model: opus-5-5

internal/routewatch/app.go

@@ -1,6 +1,8 @@
 // Package routewatch contains the primary RouteWatch type that represents a
 // running instance of the application and contains pointers to its core
-// dependencies, and is responsible for initialization.
+// dependencies, and is responsible for initialization. It also contains the
+// ASN WHOIS fetcher for background updates and the database maintainer for
+// background maintenance tasks.
 package routewatch
 
 import (

internal/routewatch/app_test.go

@@ -1,3 +1,3 @@
 package routewatch_test
 
-// Tests for routewatch package are in app_integration_test.go
+// Tests for routewatch package are in app_integration_internal_test.go