Phase 5: reply drafts — template/LLM draft, edit, SMTP send (AUD-71)

Implements Phase 5 of AGENTS.md §11 (FR-8, FR-15):

- Message detail pane (GET /partials/message) with body, recommended
  action, reply identity, template picker, editable draft, and history.
- internal/reply: OmniRoute (OpenAI-compatible) chat client and a
  template-based draft generator. All non-JEV models go through
  OmniRoute (§10).
- internal/mailops: SMTP send over smtp.gmail.com:587 with STARTTLS and
  the app password, forcing IPv4 (§9); FR-15 reply identity (send as the
  arrived-at X-Pm-Original-To address, else "Sam Rolfe"); threading via
  In-Reply-To/References; -check-smtp safe verification; and a
  [Gmail]/Sent Mail thread check.
- Migration v5 stores messages.message_id_header and drafts.sent_at;
  mailfetch parses Message-ID.
- Send is user-triggered only: CSRF + UI confirm + confirm=yes guard,
  no auto-send, duplicate-send refused. A sent reply files the original
  under Replied-to/<address> and logs every step (FR-13).
- Tests for reply, mailops SMTP/identity/thread check, store drafts and
  migration v5, and the server draft/edit/send guards.
- docs/phase5-replies.md, README, .env.example, docker-compose updated.

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

internal/reply/templates.go

@@ -0,0 +1,71 @@
+// Reply templates for Phase 5 (FR-8).
+//
+// A template is a short instruction that shapes the LLM draft. It is not the
+// final text: the model fills it in from the message, the classification, and
+// any extra note Sam types. Templates are built in for v1; a template editor is
+// not in the Phase 5 requirements.
+package reply
+
+import "strings"
+
+// Template is one reply shape.
+type Template struct {
+	ID          string
+	Name        string
+	Description string
+	// Instruction is the template-specific part of the prompt.
+	Instruction string
+}
+
+// Templates is the built-in template list, in menu order.
+var Templates = []Template{
+	{
+		ID:          "quick-ack",
+		Name:        "Quick acknowledgement",
+		Description: "Confirm receipt in one or two short sentences.",
+		Instruction: "Acknowledge that the message was received. If the sender asked for something, say when Sam will look at it. Do not promise anything Sam has not agreed to.",
+	},
+	{
+		ID:          "answer",
+		Name:        "Answer the question",
+		Description: "Answer the sender's question directly.",
+		Instruction: "Answer the sender's question directly and briefly. If the message does not contain a clear question, summarise what Sam understood and ask one clarifying question.",
+	},
+	{
+		ID:          "confirm",
+		Name:        "Confirm an arrangement",
+		Description: "Confirm a booking, time, or arrangement.",
+		Instruction: "Confirm the arrangement in the message: restate the key detail (date, time, or reference) and say it works for Sam.",
+	},
+	{
+		ID:          "decline",
+		Name:        "Politely decline",
+		Description: "Decline or say no thanks, politely.",
+		Instruction: "Politely decline the request or offer. Thank the sender and keep it warm but brief. Do not over-explain.",
+	},
+}
+
+// TemplateByID returns the template with the given id. ok is false when it is
+// unknown. The id match is case-insensitive.
+func TemplateByID(id string) (Template, bool) {
+	id = strings.ToLower(strings.TrimSpace(id))
+	for _, t := range Templates {
+		if t.ID == id {
+			return t, true
+		}
+	}
+	return Template{}, false
+}
+
+// TemplateForAction picks a sensible default template from the classifier's
+// recommended action. An unknown action falls back to a quick acknowledgement.
+func TemplateForAction(action string) Template {
+	switch strings.ToLower(strings.TrimSpace(action)) {
+	case "reply":
+		t, _ := TemplateByID("answer")
+		return t
+	default:
+		t, _ := TemplateByID("quick-ack")
+		return t
+	}
+}