feat!: apps SDK, decorator-native GPU compute with live dev sessions and a new rp CLI

[KAJdev]

This is the successor to runpod-flash, folded into the core runpod package. I know this is absolutely massive but its a port of all existing flash features plus whole new App, Model, and Secret classes, @app.task decorator for running ephemeral pods, new runtimes, and shims for injecting into custom images. (with 90% test coverage!)

Completes CON-652

app = runpod.App("inference")

@app.queue(gpu="H100", workers=(0, 3), dependencies=["vllm"], model=llama)
def chat(prompt: str): ...

chat.remote("why is the sky blue?") 

For existing Flash users

• Same control plane. Apps, environments, and builds are the same platform objects (flashApps, flashEnvironments, flashBuilds). Deployed Flash apps keep running, and this client can see and manage them (rp app list, rp undeploy).
• The decorator surface maps directly. @remote(...) shapes become @app.queue, @app.api, and @app.task, with full config parity
• migration should be as simple as: rename decorators, pip install runpod, rp deploy. A migration guide should land in docs alongside the release.
• new Secret() and Model() classes, + custom image support

Release checklist

• runpod/host#2508 merged (autocache runtime images on hosts)
• PyPI release including runpod.runtimes (e2e 12_custom_image currently pins the branch tarball via RUNPOD_PACKAGE_SPEC)
• Flash migration guide in docs; deprecation notice on runpod-flash
• Changelog: runpod config, exec, and project CLI commands removed; rp login and rp init replace them
• Post-release: verify rp update against the published version, drop the tarball note from the e2e README

Breaking changes

• CLI: config, exec, and project command groups removed; ssh list-keys and add-key renamed to ssh list and add
• Python API: additive only. Existing runpod.serverless, Endpoint, and ctl commands are unchanged.

[capy-ai]

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[github-advanced-security]

CodeQL found more than 20 potential problems in the proposed changes. Check the Files changed tab for more details.

[promptless]

Promptless prepared a documentation update related to this change.

Triggered by runpod-python PR #534

This PR introduces the apps SDK (successor to runpod-flash, folded into the core runpod package) and the new unified rp CLI. The draft adds a Flash → apps SDK migration guide, deprecation notices on the existing Flash docs, a nav entry, and a release-gated (commented-out) changelog entry. It's scoped as a release-gated draft since the apps SDK isn't published to PyPI yet.

Review: Apps SDK + Flash → apps SDK migration guide

[KAJdev]

@capy-ai review