scrypted: implement StartStop for proper lifecycle UI + clean tear-down

The Scripts 'Status and Controls' panel previously rendered Unknown
because the Provider exposed no lifecycle interface. STOP / START in
that panel didn't do anything useful — Scrypted's only option was
to unload the script entirely, which left the user's re-paste flow
relying on the constructor-time globalThis cleanup hack (and even
that didn't cover in-flight streams until 1ce49d3).

This commit makes the panel real:

  class ScryptedViewportProvider ... implements ..., StartStop
  - async start() : drain shutdown cleaners, bootstrap, running=true
  - async stop()  : drain shutdown cleaners, clear viewport+listener+
                    stream maps, running=false

  Both methods are idempotent (no-op when already in target state).
  The constructor calls start() automatically so script load still
  bootstraps without user action.

The private start() method that did the actual provisioning is
renamed to bootstrap() to free up the public name for the StartStop
contract. registerShutdownCleaners is renamed to drainShutdownCleaners
and now takes a 'reason' label so the log line distinguishes 'start:
tearing down N resources' (previous load) from 'stop: tearing down N
resources' (user-driven).

Effect on the workflow the user described:
  1. Click STOP in the Scripts UI → stop() drains every resource
     (streams, listeners, intervals) the provider currently holds.
  2. Re-paste the new script.
  3. New constructor runs → start() drains anything left behind →
     bootstrap re-discovers children + re-attaches listeners → ready.

No more accumulating ghosts of prior loads.

0 files changed, 0 insertions, 0 deletions