phase 1: HTTP server + first-run bootstrap

P1-01 chi router, slog request log, graceful shutdown via signal
  context. Health endpoint, /api/auth/login, /api/auth/logout,
  /api/bootstrap. Background sweeper for expired sessions and
  enrollment tokens (15 min cadence).

P1-04 (sessions half) HttpOnly Secure-when-TLS cookie carrying a
  base64url token; server stores SHA-256(token) so a stolen DB
  doesn't yield credentials. Unknown user and bad password collapse
  to the same 401 response code so a probe can't enumerate names.

P1-05 first-run admin bootstrap. On a fresh DB the server mints a
  one-time token and prints it to stderr inside a banner. The
  /api/bootstrap handler accepts {token, username, password},
  creates the first admin, then becomes a 409 forever.

P1-07 (partial) audit hooks fire on auth.login and auth.bootstrap.
  Full middleware-driven coverage lands with the rest of the API.

internal/server/config: env > YAML > defaults. RM_LISTEN /
  RM_DATA_DIR / RM_BASE_URL / RM_TLS_CERT / RM_TLS_KEY /
  RM_SECRET_KEY_FILE / RM_TRUSTED_PROXY (CIDR list, validated).

End-to-end smoke test passes: server boots on a fresh dir,
prints the bootstrap token, POST /api/bootstrap creates the admin,
POST /api/auth/login returns 200 with a session cookie.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

go.sum

@@ -1,5 +1,7 @@
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@@ -10,6 +12,9 @@ github.com/mattn/go-isatty v0.0.20 h1:xfD0iDuEKnDkl03q4limB+vH+GxLEtL/jb4xVJSWWE
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@@ -23,6 +28,10 @@ golang.org/x/sys v0.43.0 h1:Rlag2XtaFTxp19wS8MXlJwTvoh8ArU6ezoyFsMyCTNI=
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+gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405 h1:yhCVgyC4o1eVCa2tZl7eS0r+SDo693bJlVdllGtEeKM=
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