feat(photon): add native message effects

[arnoldfrancisca]

Summary

• Adds a Photon sidecar /send-effect endpoint backed by spectrum-ts/providers/imessage's native effect(...) builder
• Adds PhotonAdapter.send_effect(...) for text with native iMessage bubble/screen effects
• Updates Photon README and website docs to mark message effects as supported
• Adds regression coverage for the effect endpoint body shape and validation

Why

spectrum-ts already exposes iMessage effects such as slam, loud, gentle, invisible, confetti, fireworks, balloons, heart, lasers, celebration, sparkles, spotlight, and echo. This exposes the sidecar/adapter layer without adding a new model tool or changing the global tool schema.

Verification

• node --check plugins/platforms/photon/sidecar/index.mjs
• Local effect-builder smoke test with spectrum-ts/providers/imessage → effect builder ok: com.apple.messages.effect.CKConfettiEffect
• venv/bin/python -m pytest tests/plugins/platforms/photon/test_outbound_media.py -q -o 'addopts=' → 10 passed
• venv/bin/python -m pytest tests/plugins/platforms/photon -q -o 'addopts=' → 68 passed

[arnoldfrancisca]

Local verification from fork branch: uv run --extra dev pytest tests/plugins/platforms/photon -q passed (68 passed). GitHub reports mergeable=true, mergeable_state=blocked, no CI check rollup present.

[teknium1]

Thanks for exposing the Spectrum effect capability without adding a new core tool.

Problems

• PhotonAdapter.send_effect() is currently unreachable from Hermes's outbound interface. send_message accepts only send, list, react, and unreact in tools/send_message_tool.py:210-250; its live route calls adapter.send() at tools/send_message_tool.py:713-734, and the Photon standalone sender only posts to /send at plugins/platforms/photon/adapter.py:1662-1739. The README/docs therefore overstate current user-visible support.
• The added test stubs _sidecar_call, so it cannot validate the new JavaScript handler or its spectrum-ts builder/import. Current main pins spectrum-ts 8.0.0 in plugins/platforms/photon/sidecar/package.json:15-17.

Suggested changes

• Wire effects through a deliberate supported invocation path, or scope this as internal and adjust the docs accordingly.
• Add sidecar-level coverage for a supported and unsupported effect against the pinned dependency.

This PR is substantially stale relative to the current Photon sidecar, so the implementation should be salvaged onto its current structure rather than applied verbatim. This is an automated hermes-sweeper review.

[teknium1]

send_effect() has no caller in the existing delivery surface: send_message dispatches only send/list/react/unreact and its send path invokes adapter.send(). Please wire this through a deliberate supported path (including standalone behavior), or keep it internal and avoid documenting Hermes-level effect support.

[teknium1]

Merged via #73614 — cherry-picked with authorship preserved (trivially rebased over your poll PR; a follow-up hardened MESSAGE_EFFECTS against SDK builds lacking the effect surface).