Phase 6: rules editor + unsubscribe detection (AUD-72)

- FR-11 rules editor: plain-text area at /rules, saved and versioned
  (SaveRules appends a version; restore re-saves an old version), parse
  errors surfaced, one-click re-classify. The reply model now reads the
  rules document too (FR-11).
- FR-7 unsubscribe: parse and store List-Unsubscribe / List-Unsubscribe-Post
  (migration v6), detect email and web links (internal/unsubscribe), a
  domain-level ignore list, and an explicit record of what was marked. No
  code path contacts an unsubscribe link; acting on one needs Sam's approval.
- Migration v6 is additive; unsubscribe gains url/updated_at.
- Tests: detector, parser, store migration/records/candidates, rules editor,
  unsubscribe handlers, message-detail rendering.

Co-Authored-By: Paperclip <noreply@paperclip.ing>

internal/reply/draft.go

@@ -18,6 +18,10 @@ const maxPromptBodyChars = 4000
 // maxDraftChars bounds the generated body before it is stored.
 const maxDraftChars = 8000
 
+// maxRulesChars bounds how much of the user's rules document is sent to the
+// model (FR-11: the LLM reads the rules too).
+const maxRulesChars = 2000
+
 // Request is one draft request.
 type Request struct {
 	// Message is the mail being replied to.
@@ -31,6 +35,9 @@ type Request struct {
 	// Instruction is optional extra guidance Sam typed (for example "say the
 	// invoice is paid"). It is appended to the template instruction.
 	Instruction string
+	// Rules is the current rules document from the editor (FR-11). The model
+	// reads it so reply style and handling follow the same rules as triage.
+	Rules string
 	// Signer is the name used for the sign-off (default "Sam").
 	Signer string
 }
@@ -107,6 +114,11 @@ func BuildPrompt(req Request, tmpl Template) (system, user string) {
 		b.WriteString(extra)
 		b.WriteString("\n")
 	}
+	if rules := strings.TrimSpace(req.Rules); rules != "" {
+		b.WriteString("USER RULES (follow when they apply):\n")
+		b.WriteString(truncate(rules, maxRulesChars))
+		b.WriteString("\n")
+	}
 	if cat := strings.TrimSpace(req.Category); cat != "" {
 		b.WriteString("CLASSIFICATION: category=")
 		b.WriteString(cat)