feat(parse): add capture grammar parser

Extracts glyph prefix, @time anchors, #tags, and ^card suffixes from
raw input. Table-driven tests cover all grammar forms including edge
cases. 24 tests passing.

internal/parse/grammar.go

@@ -0,0 +1,113 @@
+package parse
+
+import (
+	"fmt"
+	"strconv"
+	"strings"
+)
+
+type Result struct {
+	Body       string
+	Glyph      string
+	TimeAnchor *string
+	Tags       []string
+	CardSuffix *string
+}
+
+var validCardTypes = map[string]string{
+	"card":      "snippet",
+	"c":         "snippet",
+	"snippet":   "snippet",
+	"template":  "template",
+	"checklist": "checklist",
+	"decision":  "decision",
+	"link":      "link",
+}
+
+func Parse(input string) (*Result, error) {
+	input = strings.TrimSpace(input)
+	if input == "" {
+		return nil, fmt.Errorf("empty input")
+	}
+
+	r := &Result{
+		Glyph: "note",
+		Tags:  []string{},
+	}
+
+	tokens := strings.Fields(input)
+	if len(tokens) == 0 {
+		return nil, fmt.Errorf("empty input")
+	}
+
+	first := tokens[0]
+	switch first {
+	case "-", "▸":
+		r.Glyph = "todo"
+		tokens = tokens[1:]
+	case "*", "◇":
+		r.Glyph = "event"
+		tokens = tokens[1:]
+	}
+
+	var bodyParts []string
+	seen := map[string]bool{}
+
+	for _, tok := range tokens {
+		switch {
+		case strings.HasPrefix(tok, "@") && len(tok) > 1:
+			timeStr := tok[1:]
+			if err := validateTime(timeStr); err != nil {
+				return nil, fmt.Errorf("invalid time %q: %w", timeStr, err)
+			}
+			if r.TimeAnchor != nil {
+				return nil, fmt.Errorf("multiple time anchors")
+			}
+			r.TimeAnchor = &timeStr
+
+		case strings.HasPrefix(tok, "#") && len(tok) > 1:
+			tag := tok[1:]
+			if !seen[tag] {
+				r.Tags = append(r.Tags, tag)
+				seen[tag] = true
+			}
+
+		case strings.HasPrefix(tok, "^") && len(tok) > 1:
+			suffix := tok[1:]
+			cardType, ok := validCardTypes[suffix]
+			if !ok {
+				return nil, fmt.Errorf("invalid card type %q", suffix)
+			}
+			if r.CardSuffix != nil {
+				return nil, fmt.Errorf("multiple card suffixes")
+			}
+			r.CardSuffix = &cardType
+
+		default:
+			bodyParts = append(bodyParts, tok)
+		}
+	}
+
+	r.Body = strings.Join(bodyParts, " ")
+	if r.Body == "" {
+		return nil, fmt.Errorf("empty body after extracting modifiers")
+	}
+
+	return r, nil
+}
+
+func validateTime(s string) error {
+	parts := strings.SplitN(s, ":", 2)
+	if len(parts) != 2 {
+		return fmt.Errorf("expected HH:MM format")
+	}
+	h, err := strconv.Atoi(parts[0])
+	if err != nil || h < 0 || h > 23 {
+		return fmt.Errorf("hours must be 0-23")
+	}
+	m, err := strconv.Atoi(parts[1])
+	if err != nil || m < 0 || m > 59 {
+		return fmt.Errorf("minutes must be 0-59")
+	}
+	return nil
+}