Add –tls flag to all network commands, –limit to log, –auto-install to shell init

Extend the CLI with connection and usability flags across all subcommands.
Every command that contacts the server (archive, restore, ensure, status,
list) now accepts a –tls flag that is passed through to
PwrClient::connect, controlling whether the connection uses TLS with
certificate pinning or plaintext for local testing. The log command gains
a –limit flag defaulting to 50 entries, with a summary line showing how
many entries were truncated. The shell init command supports
–auto-install which opens the shell rc file in append mode and writes
the eval line directly, providing a one-command setup experience.

Function signatures throughout main.rs are updated to thread the new
boolean parameter. The ensure command passes tls=false through to its
internal restore call since ensure is triggered from the shell wrapper
where TLS may not be configured. The list command delegates to
cmd_status with tls=false for local-only directory scanning.