feat(connection): Add LocalConnection implementation (gt-f9x.8)

Implement LocalConnection that provides local file operations, command
execution, and tmux integration:

- File ops: ReadFile, WriteFile, MkdirAll, Remove, RemoveAll, Stat, Glob, Exists
- Command exec: Exec, ExecDir, ExecEnv
- Tmux: NewSession, KillSession, SendKeys, CapturePane, HasSession, ListSessions

Uses proper error wrapping with NotFoundError and PermissionError types.
Integrates with existing internal/tmux package for session management.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

internal/connection/local.go

@@ -0,0 +1,189 @@
+package connection
+
+import (
+	"io/fs"
+	"os"
+	"os/exec"
+	"path/filepath"
+
+	"github.com/steveyegge/gastown/internal/tmux"
+)
+
+// LocalConnection implements Connection for local file and command operations.
+type LocalConnection struct {
+	tmux *tmux.Tmux
+}
+
+// NewLocalConnection creates a new local connection.
+func NewLocalConnection() *LocalConnection {
+	return &LocalConnection{
+		tmux: tmux.NewTmux(),
+	}
+}
+
+// Name returns "local" for local connections.
+func (c *LocalConnection) Name() string {
+	return "local"
+}
+
+// IsLocal returns true for local connections.
+func (c *LocalConnection) IsLocal() bool {
+	return true
+}
+
+// ReadFile reads the named file.
+func (c *LocalConnection) ReadFile(path string) ([]byte, error) {
+	data, err := os.ReadFile(path)
+	if err != nil {
+		if os.IsNotExist(err) {
+			return nil, &NotFoundError{Path: path}
+		}
+		if os.IsPermission(err) {
+			return nil, &PermissionError{Path: path, Op: "read"}
+		}
+		return nil, err
+	}
+	return data, nil
+}
+
+// WriteFile writes data to the named file.
+func (c *LocalConnection) WriteFile(path string, data []byte, perm fs.FileMode) error {
+	err := os.WriteFile(path, data, perm)
+	if err != nil {
+		if os.IsPermission(err) {
+			return &PermissionError{Path: path, Op: "write"}
+		}
+		return err
+	}
+	return nil
+}
+
+// MkdirAll creates a directory and all parent directories.
+func (c *LocalConnection) MkdirAll(path string, perm fs.FileMode) error {
+	err := os.MkdirAll(path, perm)
+	if err != nil {
+		if os.IsPermission(err) {
+			return &PermissionError{Path: path, Op: "mkdir"}
+		}
+		return err
+	}
+	return nil
+}
+
+// Remove removes the named file or empty directory.
+func (c *LocalConnection) Remove(path string) error {
+	err := os.Remove(path)
+	if err != nil {
+		if os.IsNotExist(err) {
+			return nil // Already gone
+		}
+		if os.IsPermission(err) {
+			return &PermissionError{Path: path, Op: "remove"}
+		}
+		return err
+	}
+	return nil
+}
+
+// RemoveAll removes the named file or directory and any children.
+func (c *LocalConnection) RemoveAll(path string) error {
+	err := os.RemoveAll(path)
+	if err != nil {
+		if os.IsPermission(err) {
+			return &PermissionError{Path: path, Op: "remove"}
+		}
+		return err
+	}
+	return nil
+}
+
+// Stat returns file info for the named file.
+func (c *LocalConnection) Stat(path string) (FileInfo, error) {
+	fi, err := os.Stat(path)
+	if err != nil {
+		if os.IsNotExist(err) {
+			return nil, &NotFoundError{Path: path}
+		}
+		if os.IsPermission(err) {
+			return nil, &PermissionError{Path: path, Op: "stat"}
+		}
+		return nil, err
+	}
+	return FromOSFileInfo(fi), nil
+}
+
+// Glob returns the names of all files matching the pattern.
+func (c *LocalConnection) Glob(pattern string) ([]string, error) {
+	matches, err := filepath.Glob(pattern)
+	if err != nil {
+		return nil, err
+	}
+	return matches, nil
+}
+
+// Exists returns true if the path exists.
+func (c *LocalConnection) Exists(path string) (bool, error) {
+	_, err := os.Stat(path)
+	if err != nil {
+		if os.IsNotExist(err) {
+			return false, nil
+		}
+		return false, err
+	}
+	return true, nil
+}
+
+// Exec runs a command and returns its combined output.
+func (c *LocalConnection) Exec(cmd string, args ...string) ([]byte, error) {
+	return exec.Command(cmd, args...).CombinedOutput()
+}
+
+// ExecDir runs a command in the specified directory.
+func (c *LocalConnection) ExecDir(dir, cmd string, args ...string) ([]byte, error) {
+	command := exec.Command(cmd, args...)
+	command.Dir = dir
+	return command.CombinedOutput()
+}
+
+// ExecEnv runs a command with additional environment variables.
+func (c *LocalConnection) ExecEnv(env map[string]string, cmd string, args ...string) ([]byte, error) {
+	command := exec.Command(cmd, args...)
+	command.Env = os.Environ()
+	for k, v := range env {
+		command.Env = append(command.Env, k+"="+v)
+	}
+	return command.CombinedOutput()
+}
+
+// TmuxNewSession creates a new tmux session.
+func (c *LocalConnection) TmuxNewSession(name, dir string) error {
+	return c.tmux.NewSession(name, dir)
+}
+
+// TmuxKillSession terminates a tmux session.
+func (c *LocalConnection) TmuxKillSession(name string) error {
+	return c.tmux.KillSession(name)
+}
+
+// TmuxSendKeys sends keys to a tmux session.
+func (c *LocalConnection) TmuxSendKeys(session, keys string) error {
+	return c.tmux.SendKeys(session, keys)
+}
+
+// TmuxCapturePane captures the last N lines from a tmux pane.
+func (c *LocalConnection) TmuxCapturePane(session string, lines int) (string, error) {
+	return c.tmux.CapturePane(session, lines)
+}
+
+// TmuxHasSession returns true if the session exists.
+func (c *LocalConnection) TmuxHasSession(name string) (bool, error) {
+	return c.tmux.HasSession(name)
+}
+
+// TmuxListSessions returns all tmux session names.
+func (c *LocalConnection) TmuxListSessions() ([]string, error) {
+	return c.tmux.ListSessions()
+}
+
+// Verify LocalConnection implements Connection.
+var _ Connection = (*LocalConnection)(nil)