Suggestions: stop re-nagging resolved edits + fix typographic anchoring

Two fixes for the "accept Petal's change, then it nags about the same
sentence moments later" report:

- replacePending now suppresses any freshly-generated suggestion whose
  original->replacement matches one the user already accepted or
  dismissed for that doc. The model has no memory between passes, so
  without this it re-proposes the identical edit on the next checkpoint.

- findRange anchored suggestions by exact string match, which missed
  whenever the model echoed an `original` with plain ASCII (straight
  quotes, --, ...) while the document held the Typography-converted
  glyphs (curly quotes, em-dash, single-char ellipsis). The miss meant
  no highlight AND a silent no-op on accept, which then fed the re-nag
  above. foldTypography canonicalizes those variants (with a source
  index map for length changes) so matching survives the mismatch.

Covered by a server-side regression test (accept+dismiss then re-check
returns nothing) and frontend unit tests for the fold and anchoring.

Claude-Session: https://claude.ai/code/session_016Yr6jELuRc7hyzYLccQKZd

internal/suggestions/handlers.go

@@ -154,6 +154,14 @@ var (
 // replacePending swaps a document's pending suggestions within one family for a
 // fresh batch in a single transaction. Accepted/rejected suggestions and the
 // other family's pending rows are left untouched.
+//
+// Suggestions the user already accepted or dismissed are suppressed from the
+// fresh batch: the model has no memory between passes, so without this it would
+// re-propose the identical edit on the very next checkpoint — re-nagging a
+// sentence the user already resolved. This matters most when an accept silently
+// no-ops (the `original` text couldn't be anchored in the editor, so the doc
+// never changed): the sentence is unaltered, yet the user shouldn't see the same
+// card again.
 func (h *Handler) replacePending(docID, contentText string, raw []llm.RawSuggestion, scope pendingScope) error {
 	tx, err := h.DB.Begin()
 	if err != nil {
@@ -168,7 +176,15 @@ func (h *Handler) replacePending(docID, contentText string, raw []llm.RawSuggest
 		return err
 	}
 
+	actioned, err := actionedKeys(tx, docID)
+	if err != nil {
+		return err
+	}
+
 	for _, s := range raw {
+		if _, seen := actioned[suggestionKey(s.Original, s.Replacement)]; seen {
+			continue
+		}
 		typ := scope.forceType
 		if typ == "" {
 			typ = normalizeType(s.Type)
@@ -186,6 +202,39 @@ func (h *Handler) replacePending(docID, contentText string, raw []llm.RawSuggest
 	return tx.Commit()
 }
 
+// actionedKeys returns the set of original→replacement keys the user has already
+// accepted or rejected for this document, so a fresh checkpoint can skip
+// re-proposing them. Keyed on the trimmed original+replacement pair, matching the
+// normalization ParseCheckpoint applies, so a genuinely different edit on the same
+// sentence is not suppressed.
+func actionedKeys(tx *sql.Tx, docID string) (map[string]struct{}, error) {
+	rows, err := tx.Query(
+		`SELECT original, replacement FROM suggestions
+		  WHERE doc_id = ? AND status IN (?, ?)`,
+		docID, db.SuggestionStatusAccepted, db.SuggestionStatusRejected,
+	)
+	if err != nil {
+		return nil, err
+	}
+	defer rows.Close()
+
+	keys := make(map[string]struct{})
+	for rows.Next() {
+		var original, replacement string
+		if err := rows.Scan(&original, &replacement); err != nil {
+			return nil, err
+		}
+		keys[suggestionKey(original, replacement)] = struct{}{}
+	}
+	return keys, rows.Err()
+}
+
+// suggestionKey is the dedup identity for a suggestion: its trimmed original and
+// replacement text. Two suggestions with the same key are "the same edit."
+func suggestionKey(original, replacement string) string {
+	return strings.TrimSpace(original) + "\x00" + strings.TrimSpace(replacement)
+}
+
 // listForDoc returns the document's current pending suggestions (used when the
 // editor loads a document, before any new checkpoint fires).
 func (h *Handler) listForDoc(w http.ResponseWriter, r *http.Request) {