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/store/schema.sql

@@ -21,6 +21,10 @@ CREATE TABLE IF NOT EXISTS messages (
     -- Phase 5 (FR-8): the RFC822 Message-ID header. A reply sets In-Reply-To and
     -- References to it so Gmail files the reply in the same thread.
     message_id_header TEXT,
+    -- Phase 6 (FR-7): the raw RFC 2369/8058 unsubscribe headers, stored so the
+    -- detector can run without a refetch.
+    list_unsubscribe        TEXT,
+    list_unsubscribe_post   TEXT,
     from_addr       TEXT,
     to_addr         TEXT,
     subject         TEXT,
@@ -94,11 +98,16 @@ CREATE TABLE IF NOT EXISTS actions_log (
 CREATE INDEX IF NOT EXISTS idx_actions_log_message ON actions_log (message_id);
 CREATE INDEX IF NOT EXISTS idx_actions_log_created ON actions_log (created_at);
 
--- FR-7: unsubscribe tracker and ignore list.
+-- FR-7: unsubscribe tracker and ignore list. `status` is 'ignored' for a domain
+-- on the ignore list, or 'done' for a domain Sam has recorded as unsubscribed.
+-- The app never follows a link itself: it only marks and records (AUD-72).
 CREATE TABLE IF NOT EXISTS unsubscribe (
     id          INTEGER PRIMARY KEY AUTOINCREMENT,
     domain      TEXT    NOT NULL UNIQUE,
     status      TEXT    NOT NULL DEFAULT 'done' CHECK (status IN ('done', 'ignored')),
+    -- url records the link that was detected or marked (Phase 6).
+    url         TEXT    NOT NULL DEFAULT '',
+    updated_at  TEXT,
     created_at  TEXT    NOT NULL DEFAULT (datetime('now'))
 );