feat(photon): upgrade to spectrum-ts 3.0.0 (pinned) with markdown + reactions

Pin spectrum-ts to exactly 3.0.0 (was ^1.18.0 plus an `npm install
spectrum-ts@latest` on every setup) so breaking SDK majors can't take
down fresh installs silently; `hermes photon setup` now runs `npm ci`.
Upgrade procedure documented in the README.

Migrate resolveSpace to the v3 namespace API: `im.space.create(phone)`
for DMs and `im.space.get(id)` for everything else — group spaces are
now rehydratable from their persisted id after a sidecar restart, which
v1 could not do.

Markdown: replies go out via the v3 `markdown()` builder (iMessage
renders natively; other Spectrum platforms degrade to plain text).
`PHOTON_MARKDOWN=false` reverts to the stripped plain-text path.

Reactions, behind PHOTON_REACTIONS (default off): lifecycle tapbacks
(👀 while processing, 👍/👎 on completion) via new sidecar /react and
/unreact endpoints with per-target reaction-handle tracking, and user
tapbacks on bot-sent messages routed to the agent as synthetic
`reaction:added:<emoji>` events.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

plugins/platforms/photon/sidecar/package.json

@@ -1,7 +1,7 @@
 {
   "name": "@hermes-agent/photon-sidecar",
   "private": true,
-  "version": "0.2.0",
+  "version": "0.3.0",
   "description": "Spectrum-ts bridge for the Hermes Agent Photon platform plugin.",
   "type": "module",
   "main": "index.mjs",
@@ -12,7 +12,7 @@
     "node": ">=18.17"
   },
   "dependencies": {
-    "spectrum-ts": "^1.18.0"
+    "spectrum-ts": "3.0.0"
   },
   "overrides": {
     "protobufjs": "8.6.1",