Prepare the next browse release by versioning the package on `main`.

What this PR does:
- bumps `packages/cli/package.json` to `0.8.4`
- updates the browse changelog
- consumes the pending browse changesets

After this PR merges, the `Release` workflow on `main` will publish
`browse@0.8.4` from that exact commit using `pnpm pack` + `npm publish
--provenance`.


<!-- This is an auto-generated description by cubic. -->
---
## Summary by cubic
Prepare the `browse@0.8.4` release by bumping the CLI version, updating
the changelog, and consuming pending changesets. After merge, the
Release workflow on `main` will publish from this commit using `pnpm
pack` + `npm publish --provenance`.

- **Bug Fixes**
- `browse templates list` now shows the full catalog (requests with
scope=all).
- `browse skills add` now fails fast on unknown skills, surfaces real
error output, records telemetry, and prints guidance when no arg is
provided.

<sup>Written for commit 9bdef794d006222e6382de31bf04b900357f2eb1.
Summary will update on new commits.</sup>

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