Re-vendor the canonical files from sneak/prompts at dd4027b (closes #213)

Linting and testing become the lint and test phases of the Dockerfile,
and the build stage depends on both. Dockerfile.lint, CHECK_EPOCH and
the tests that checked them are removed. Every docker build in script/
passes --no-cache, and script/cibuild runs script/bootstrap first. The
image takes its version from the VERSION build arg or git describe, and
still stamps the commit and its date from .git. The golangci-lint
v2.14.0 findings are fixed in the code. The rules in CLAUDE.md move into
AGENTS.md. IsDevVersion now counts "unknown", the version script/docker
stamps outside a git checkout.

Model: opus-5-5

internal/database/file_chunks.go

@@ -253,7 +253,7 @@ func (r *FileChunkRepository) CreateBatch(
 			args = append(args, fc.FileID.String(), fc.Idx, fc.ChunkHash.String())
 		}
 
-		query += querySb211.String() //nolint:gosec // G202: appends "?" placeholders only
+		query += querySb211.String()
 
 		query += " ON CONFLICT(file_id, idx) DO NOTHING"