Gitea setup: Core Rule Set blocks attacks, not ordinary Gitea traffic (closes #198)

The Gitea setup runs the Core Rule Set in block mode. Rules that refused
ordinary Gitea requests are switched off only where they misfired:

- deploy/gitea/crs-exclusions.conf, loaded through the new setting
  SWWAF_CORE_RULE_SET_EXCLUSIONS_FILE before the Core Rule Set's rules,
  covers Gitea's search, file-name and branch-name fields, Referer, file
  paths, API attachment names and Actions artifact uploads;
- smallwebwaf's defaults gain a seventh change: the registry upload
  path's from parameter skips 932260.

A file that cannot be read, does not parse or names an id from 900000
to 900999 stops servewaf at start, in every mode. internal/waf's tests
and script/gitea-setup send the recorded requests in
internal/waf/testdata/gitea-requests.txt and three attacks.

Model: opus-5-5

internal/config/config_test.go

@@ -87,6 +87,7 @@ const (
 	wafDisabledRules     = "SWWAF_WAF_DISABLED_RULES"
 	wafExemptPaths       = "SWWAF_WAF_EXEMPT_PATHS"
 	wafBodyLimit         = "SWWAF_WAF_BODY_LIMIT"
+	exclusionsFile       = "SWWAF_CORE_RULE_SET_EXCLUSIONS_FILE"
 	trapPaths            = "SWWAF_TRAP_PATHS"
 	errorBurstThreshold  = "SWWAF_ERROR_BURST_THRESHOLD"
 	logRemoteURL         = "SWWAF_LOG_REMOTE_URL"
@@ -539,13 +540,14 @@ func TestCoreRuleSetSettings(t *testing.T) {
 			environment{
 				wafMode: config.WAFModeDetect, wafParanoiaLevel: "4", wafAnomalyThreshold: "10",
 				wafDisabledRules: "942100, 920350", wafExemptPaths: "/api/, /static/",
-				wafBodyLimit: "32K",
+				wafBodyLimit: "32K", exclusionsFile: "/etc/smallwebwaf/crs-exclusions.conf",
 			},
 			config.Config{
 				WAFMode: config.WAFModeDetect, WAFParanoiaLevel: 4, WAFAnomalyThreshold: 10,
-				WAFDisabledRules: []int{942100, 920350},
-				WAFExemptPaths:   []string{"/api/", "/static/"},
-				WAFBodyLimit:     32 << 10,
+				WAFDisabledRules:          []int{942100, 920350},
+				WAFExemptPaths:            []string{"/api/", "/static/"},
+				WAFBodyLimit:              32 << 10,
+				CoreRuleSetExclusionsFile: "/etc/smallwebwaf/crs-exclusions.conf",
 			},
 		},
 		{
@@ -565,7 +567,8 @@ func TestCoreRuleSetSettings(t *testing.T) {
 			WAFMode: cfg.WAFMode, WAFParanoiaLevel: cfg.WAFParanoiaLevel,
 			WAFAnomalyThreshold: cfg.WAFAnomalyThreshold,
 			WAFDisabledRules:    cfg.WAFDisabledRules, WAFExemptPaths: cfg.WAFExemptPaths,
-			WAFBodyLimit: cfg.WAFBodyLimit,
+			WAFBodyLimit:              cfg.WAFBodyLimit,
+			CoreRuleSetExclusionsFile: cfg.CoreRuleSetExclusionsFile,
 		}
 		if !reflect.DeepEqual(got, tc.want) {
 			t.Errorf("%v gave\n%+v\nwant\n%+v", tc.env, got, tc.want)
@@ -2327,6 +2330,7 @@ func TestLogsEachSettingWithItsValue(t *testing.T) {
 		wafDisabledRules:     defaultWAFDisabledRules,
 		wafExemptPaths:       "",
 		wafBodyLimit:         off,
+		exclusionsFile:       "",
 		trapPaths:            "",
 		errorBurstThreshold:  "30",
 		logRemoteURL:         "",