chore(orb): target 3.4.0 for the next beta channel (#8274)

orb-v3.3.0 shipped stable, so the beta cutter is idle until the manifest's
declared target moves forward. The calibration-expansion epic's merges since
(per-repo loosening #8264, reviewer votes #8265, tightening #8267, AMS loop
#8270, counterfactual replay #8271) are feats — the inferred bump is minor,
so the next automated snapshot targets orb-v3.4.0-beta.1.

Author: JSONbored

orb-manifest.json

@@ -1,4 +1,4 @@
 {
-  "version": "3.3.0",
+  "version": "3.4.0",
   "description": "Source of truth for the self-hostable loopover-orb container image's target release version (ghcr.io/jsonbored/loopover-selfhost). Bumped by a maintainer when a feat/fix/breaking change since the last stable orb-v tag warrants moving to a new target version -- scripts/orb-release-core.ts and .github/workflows/orb-beta-release.yml read this file to decide what version the next automated beta snapshot targets. Promoting a beta to a stable orb-vX.Y.Z release is still a manual `git tag` -- this manifest only drives the automated beta channel."
 }