SPEC and README: rule set changes, error bursts, admin bans, GeoJS answers (closes #6)

Address the second review of the spec update. The Core Rule Set allows
PUT, PATCH and DELETE and the headers git and curl send, inspects only
bodies it can read, leaves responses alone, and by default switches off
the rules that refuse a code forge's ordinary files, uploads and git
traffic. The error burst counts only the sidecar's own refusals. Bans an
admin made are never dropped. A limit ban resets the client's counters.
GeoJS answers move to their own `lookups.json`. The spec now says which
address is the client when every forwarded address is trusted, that the
exclusive country list refuses private addresses, which are never sent to
GeoJS, what `close` gives behind traefik, and Spamhaus's terms for DROP.

Model: opus-5-5

README.md

@@ -79,7 +79,8 @@ goes through the candidates one by one.
       running;
     - the OWASP Core Rule Set, run by the Coraza engine, refusing the requests
       it flags;
-    - trap paths and bursts of error responses.
+    - trap paths, and a ban for a client that the rule files or the Core Rule
+      Set refuse again and again.
 - Bans:
     - a clear sign of attack, such as a probe for a `.env` file or a scanner's
       user agent, bans for seven days on the first request, and any further
@@ -102,8 +103,8 @@ goes through the candidates one by one.
   fields, the decision taken and why, AS number and country, and timings.
   Optionally also sent to a remote syslog server.
 - Prometheus metrics on their own port.
-- State (bans with their notes, each client's counters, history and lookup
-  answer, the reputation cache, the alerting state) held in memory and kept in
+- State (bans with their notes, each client's counters and history, the GeoJS
+  answers, the reputation cache, the alerting state) held in memory and kept in
   readable JSON files, written regularly and at every stop, so a restart loses
   nothing. Edit a file, or add a rule file, and the running `smallwebwaf` picks
   up the change. Nothing is read from disk while serving a request.
@@ -131,8 +132,9 @@ For each request `smallwebwaf`:
   client at once for a clear sign of attack;
 - forwards it to the app and streams the response back, within the size and time
   limits;
-- counts the bytes and any error response, bans the client if it broke a limit,
-  updates its history, sends any alerts that are due, and writes the log line.
+- counts the bytes and any refusal by the rule files or the Core Rule Set, bans
+  the client if it broke a limit, updates its history, sends any alerts that are
+  due, and writes the log line.
 
 A minimal deployment beside an app in docker-compose. `UPSTREAM_URL` is the only
 setting:
@@ -204,6 +206,11 @@ request. GeoJS publishes no rate limit but may block a caller it thinks asks too
 much; while it is not answering, new visitors count as coming from an unknown
 country, which `EXCLUSIVELY_ALLOWED_COUNTRIES` refuses.
 
+Neither source can place a private address, so a client on one, such as a
+visitor on your local network, another container or your monitoring, has no
+country: `EXCLUSIVELY_ALLOWED_COUNTRIES` refuses it unless you list it in
+`ALLOW_NETS`. Such addresses are never sent to GeoJS.
+
 ## Documents
 
 - [`SPEC.md`](SPEC.md): the design.