fix(pi): keep decorative startup UI out of RPC mode

[tajquitgenius]

What changed

• Show Ponytail’s styled status only in Pi’s local TUI.
• Show the startup-loaded notification only in the local TUI.
• Keep Ponytail prompt injection and explicit command notifications active in RPC mode.

Why

Pi RPC forwards notify and setStatus calls to remote clients. The status contains terminal color escapes, so browser clients show both an unnecessary startup toast and a block of raw escape characters above the composer. These values are decorative terminal UI, not remote functionality.

Checks

• node --test pi-extension/test/*.test.js (24 passed)
• Added an RPC startup regression that verifies no notification or status while the Ponytail instructions still inject.
• The full root suite has one unrelated timing-sensitive pandas correctness failure on this machine.