[FEATURE] Add a CLI command to hand off a running local session to the cloud (local→web, the inverse of `--teleport`)

Preflight Checklist

• [x] I have searched existing requests and this feature hasn't been requested yet
• [x] This is a single feature request (not multiple features)

Problem Statement

From the CLI, session handoff is one-way: --teleport pulls a cloud session down into the terminal, but there is no way to push an already-running local session up to the cloud. Today the only mechanism that lifts a live local session to the web is the Desktop app's "Continue in" menu.

That mechanism is unreachable for a large slice of developers:

• There is no Claude Desktop app for Linux (official guidance is "use the CLI").
• On Windows, the Desktop app's embedded shell runs commands in the Windows environment, not inside WSL2, so it can't see WSL-resident files (or can, as a network mount, but that's a setup that is useless for anything beyond silly demos -- aka, actual work), toolchains, or the running session (see #12506, #49933).

Net effect: developers whose primary environment is WSL2 or native Linux — i.e. a substantial share of the professional dev audience — have no supported path to move an in-progress session to the cloud before stepping away or going offline. --remote only starts a new cloud session; it does not carry over the current conversation/context.

Proposed Solution

A CLI-native command that pushes the current local session (conversation history + working branch) to a cloud session — effectively the inverse of --teleport. For example /teleport --to-cloud or claude --push-remote, reusing the git preconditions teleport already enforces (clean state / pushed branch).

This must not require a GUI. The capability is missing at the CLI layer; gating it behind a desktop surface is the actual defect. A headless / terminal-only path is the entire point of the request — I'm happy to do all the git hygiene the handoff needs, I just need the handoff to exist without a desktop app.

Alternative Solutions

• Desktop "Continue in" — nonexistent on Linux, non-functional for WSL2 on Windows.
• --remote — starts a fresh session, discards current context.
• Manual git push + --remote with a re-explained prompt — works, but loses conversation state and is fully manual.

Priority

Critical - Blocking my work

Feature Category

CLI commands and flags

Use Case Example

1. Late enough that office AC turned off.
2. Long prompt work ahead -- Ooh, I can move the session online so I can continue as soon as I get home.
3. /remote-control

(Yes, now I know it's bogus. But I don't know what to type as a "use case" for something that you clearly have as a feature, so, you know -- "the usual".)

Additional Context

1. A few minutes late: WTF.
2. Another N minutes later: claude.ai has a definitive answer -- "Anthropic doesn't care about you".