Lower the default request and byte limits (closes #193)

New defaults, as sneak approved: 120 requests a minute, 1,500 an hour and 6,000 a day; bytes off a minute, 50G an hour and 100G a day. The README, `SPEC.md`, `docs/settings.md` and `docs/gitea.md` give the new figures and reasoning, and point Actions runners and shared addresses at `SWWAF_RATE_LIMIT_EXEMPT_NETS`. The README examples now hold against the new defaults.

An Actions runner that is not exempted makes more requests an hour than the new limit and will be banned.

Model: opus-5-5

internal/config/config_test.go

@@ -244,9 +244,9 @@ func TestDefaults(t *testing.T) {
 	wantSettings(t, cfg, config.Config{
 		ListenAddr:           ":8080",
 		Observe:              false,
-		RateLimitPerMinute:   500,
-		RateLimitPerHour:     20000,
-		RateLimitPerDay:      300000,
+		RateLimitPerMinute:   120,
+		RateLimitPerHour:     1500,
+		RateLimitPerDay:      6000,
 		BanResponse:          403,
 		LimitBanDuration:     time.Hour,
 		LimitBanRepeatWindow: 24 * time.Hour,
@@ -266,8 +266,8 @@ func TestDefaults(t *testing.T) {
 		LookupSource: defaultLookupSource, LookupTimeout: 800 * time.Millisecond,
 	})
 	wantByteLimitSettings(t, cfg, config.Config{
-		BytesLimitPerMinute: 4 << 30, BytesLimitPerHour: 20 << 30,
-		BytesLimitPerDay: 200 << 30, BytesCount: "both",
+		BytesLimitPerMinute: 0, BytesLimitPerHour: 50 << 30,
+		BytesLimitPerDay: 100 << 30, BytesCount: "both",
 	})
 
 	wantNetblocks(t, cfg.AllowNets)
@@ -308,7 +308,7 @@ func TestNoSingleRequestBreaksAByteLimitAtTheDefaults(t *testing.T) {
 	for _, limit := range []int64{
 		cfg.BytesLimitPerMinute, cfg.BytesLimitPerHour, cfg.BytesLimitPerDay,
 	} {
-		if largest > limit {
+		if limit != 0 && largest > limit { // 0 is off
 			t.Errorf("a request of %d bytes breaks the byte limit of %d", largest, limit)
 		}
 	}
@@ -2271,12 +2271,12 @@ func TestLogsEachSettingWithItsValue(t *testing.T) {
 		rateLimitExemptNets:  "",
 		denyNets:             "",
 		rateLimitPerMinute:   "45",
-		rateLimitPerHour:     "20000",
-		rateLimitPerDay:      "300000",
+		rateLimitPerHour:     "1500",
+		rateLimitPerDay:      "6000",
 		rateLimitExemptPaths: "",
-		bytesLimitPerMinute:  "4G",
-		bytesLimitPerHour:    "20G",
-		bytesLimitPerDay:     "200G",
+		bytesLimitPerMinute:  "off",
+		bytesLimitPerHour:    "50G",
+		bytesLimitPerDay:     "100G",
 		bytesCount:           "both",
 		lookupSource:         defaultLookupSource,
 		lookupDBPath:         "",