Move the example config to configs/, delete scripts/ and CONVENTIONS.md (closes #97)

config.example.yml moves unchanged to configs/config.example.yml, the
directory REPO_POLICIES.md names for configuration examples. README.md,
the comments in internal/config/config.go and the startup error for the
placeholder signing key name the new path. scripts/manual-test.sh and
its directory are deleted: each check it made against a running server
is now a handler test in internal/handlers. CONVENTIONS.md, a reformatted
copy of the Go HTTP server conventions, is deleted, as REPO_POLICIES.md
links the canonical document.

Model: opus-5-5

TODO.md

@@ -31,6 +31,14 @@ P2: security: referer blacklist
 
 # Completed Steps
 
+- 2026-10-04 fewer files in the repository root (closes #97):
+  `config.example.yml` moved unchanged to `configs/config.example.yml`, and
+  `README.md`, the comments in `internal/config/config.go` and the startup error
+  for the placeholder signing key name the new path; `scripts/manual-test.sh`
+  and its directory are deleted, as the handler tests in `internal/handlers`
+  cover every check it made except fetching a real image from the internet;
+  `CONVENTIONS.md` is deleted, as `REPO_POLICIES.md` links the canonical Go HTTP
+  server conventions.
 - 2026-10-04 logging in, logging out, the URL generator and `/v1/e/` have
   handler tests (closes #77): new tests in `internal/handlers`, with no
   network, check that `GET /` without a login session shows the login form; a