Add snippet/command library with CRUD and send-to-session

Full command snippet library for saving and sending reusable commands:

Backend:
- SQLite migration 003 creates snippets table
- Snippet model with name, command, description, folder, tags
- Store CRUD methods and API endpoints

Frontend:
- SnippetLibrary class with searchable list + detail/editor split view
- Create, edit, delete snippets in modal dialog
- 'Send to Session' button writes command to active terminal
- 'Send Snippet' option in terminal right-click context menu
- Ctrl+Shift+S keyboard shortcut to open library

internal/api/api.go

@@ -574,6 +574,54 @@ func (s *Service) ListAuditEntries(limit int) ([]models.AuditEntry, error) {
 	return result, nil
 }
 
+// ---------------------------------------------------------------------------
+// Snippets (command library)
+// ---------------------------------------------------------------------------
+
+// ListSnippets returns all saved command snippets.
+func (s *Service) ListSnippets() ([]models.Snippet, error) {
+	snippets, err := s.store.ListSnippets()
+	if err != nil {
+		return nil, err
+	}
+	result := make([]models.Snippet, len(snippets))
+	for i, sn := range snippets {
+		result[i] = *sn
+	}
+	return result, nil
+}
+
+// CreateSnippet saves a new command snippet.
+func (s *Service) CreateSnippet(snippet models.Snippet) (models.Snippet, error) {
+	if snippet.ID == "" {
+		snippet.ID = uuid.New().String()
+	}
+	now := time.Now()
+	snippet.CreatedAt = now
+	snippet.UpdatedAt = now
+	if snippet.Tags == nil {
+		snippet.Tags = []string{}
+	}
+	if err := s.store.CreateSnippet(&snippet); err != nil {
+		return models.Snippet{}, fmt.Errorf("failed to create snippet: %w", err)
+	}
+	return snippet, nil
+}
+
+// UpdateSnippet updates an existing command snippet.
+func (s *Service) UpdateSnippet(snippet models.Snippet) (models.Snippet, error) {
+	snippet.UpdatedAt = time.Now()
+	if err := s.store.UpdateSnippet(&snippet); err != nil {
+		return models.Snippet{}, fmt.Errorf("failed to update snippet: %w", err)
+	}
+	return snippet, nil
+}
+
+// DeleteSnippet removes a command snippet by ID.
+func (s *Service) DeleteSnippet(id string) error {
+	return s.store.DeleteSnippet(id)
+}
+
 // ---------------------------------------------------------------------------
 // Utility
 // ---------------------------------------------------------------------------

internal/models/models.go

@@ -256,3 +256,15 @@ type AuditEntry struct {
 	SessionID string    `json:"sessionId,omitempty"`
 	Details   string    `json:"details"`
 }
+
+// Snippet stores a reusable command for the snippet library.
+type Snippet struct {
+	ID          string    `json:"id"`
+	Name        string    `json:"name"`
+	Command     string    `json:"command"`
+	Description string    `json:"description"`
+	Folder      string    `json:"folder"`
+	Tags        []string  `json:"tags"`
+	CreatedAt   time.Time `json:"createdAt"`
+	UpdatedAt   time.Time `json:"updatedAt"`
+}

internal/storage/migrations/003_snippets.sql

@@ -0,0 +1,15 @@
+-- Migration 003: Add snippets table for the command snippet library.
+-- Stores reusable commands that can be sent to active sessions.
+
+CREATE TABLE IF NOT EXISTS snippets (
+    id TEXT PRIMARY KEY,
+    name TEXT NOT NULL,
+    command TEXT NOT NULL,
+    description TEXT NOT NULL DEFAULT '',
+    folder TEXT NOT NULL DEFAULT '',
+    tags TEXT NOT NULL DEFAULT '[]',
+    created_at TEXT NOT NULL DEFAULT (datetime('now')),
+    updated_at TEXT NOT NULL DEFAULT (datetime('now'))
+);
+
+INSERT INTO schema_version (version, applied_at) VALUES (3, datetime('now'));

internal/storage/store.go

@@ -709,3 +709,82 @@ func nullableJSON(ptr interface{}, data []byte) interface{} {
 	}
 	return string(data)
 }
+
+// ---------------------------------------------------------------------------
+// Snippet CRUD
+// ---------------------------------------------------------------------------
+
+// CreateSnippet inserts a new snippet into the database.
+func (s *Store) CreateSnippet(snippet *models.Snippet) error {
+	tagsJSON, _ := json.Marshal(snippet.Tags)
+	_, err := s.db.Exec(`INSERT INTO snippets (id, name, command, description, folder, tags, created_at, updated_at)
+		VALUES (?, ?, ?, ?, ?, ?, ?, ?)`,
+		snippet.ID, snippet.Name, snippet.Command, snippet.Description,
+		snippet.Folder, string(tagsJSON),
+		snippet.CreatedAt.Format(time.RFC3339),
+		snippet.UpdatedAt.Format(time.RFC3339),
+	)
+	return err
+}
+
+// UpdateSnippet updates an existing snippet.
+func (s *Store) UpdateSnippet(snippet *models.Snippet) error {
+	tagsJSON, _ := json.Marshal(snippet.Tags)
+	_, err := s.db.Exec(`UPDATE snippets SET name=?, command=?, description=?, folder=?, tags=?, updated_at=? WHERE id=?`,
+		snippet.Name, snippet.Command, snippet.Description,
+		snippet.Folder, string(tagsJSON),
+		snippet.UpdatedAt.Format(time.RFC3339),
+		snippet.ID,
+	)
+	return err
+}
+
+// DeleteSnippet removes a snippet by ID.
+func (s *Store) DeleteSnippet(id string) error {
+	_, err := s.db.Exec(`DELETE FROM snippets WHERE id = ?`, id)
+	return err
+}
+
+// ListSnippets returns all snippets ordered by name.
+func (s *Store) ListSnippets() ([]*models.Snippet, error) {
+	rows, err := s.db.Query(`SELECT id, name, command, description, folder, tags, created_at, updated_at FROM snippets ORDER BY name ASC`)
+	if err != nil {
+		return nil, err
+	}
+	defer rows.Close()
+
+	var snippets []*models.Snippet
+	for rows.Next() {
+		sn := &models.Snippet{}
+		var tagsStr, createdAt, updatedAt string
+		if err := rows.Scan(&sn.ID, &sn.Name, &sn.Command, &sn.Description, &sn.Folder, &tagsStr, &createdAt, &updatedAt); err != nil {
+			return nil, err
+		}
+		_ = json.Unmarshal([]byte(tagsStr), &sn.Tags)
+		if sn.Tags == nil {
+			sn.Tags = []string{}
+		}
+		sn.CreatedAt, _ = time.Parse(time.RFC3339, createdAt)
+		sn.UpdatedAt, _ = time.Parse(time.RFC3339, updatedAt)
+		snippets = append(snippets, sn)
+	}
+	return snippets, rows.Err()
+}
+
+// GetSnippet returns a single snippet by ID.
+func (s *Store) GetSnippet(id string) (*models.Snippet, error) {
+	sn := &models.Snippet{}
+	var tagsStr, createdAt, updatedAt string
+	err := s.db.QueryRow(`SELECT id, name, command, description, folder, tags, created_at, updated_at FROM snippets WHERE id = ?`, id).
+		Scan(&sn.ID, &sn.Name, &sn.Command, &sn.Description, &sn.Folder, &tagsStr, &createdAt, &updatedAt)
+	if err != nil {
+		return nil, err
+	}
+	_ = json.Unmarshal([]byte(tagsStr), &sn.Tags)
+	if sn.Tags == nil {
+		sn.Tags = []string{}
+	}
+	sn.CreatedAt, _ = time.Parse(time.RFC3339, createdAt)
+	sn.UpdatedAt, _ = time.Parse(time.RFC3339, updatedAt)
+	return sn, nil
+}