docs: link install to releases page, add release-process guide

Replaces the "build from source only" Install section with a
Releases-page download path plus a SmartScreen note, and adds
docs/release-process.md so the tag-bump-build flow is captured for
future maintainers.

docs/release-process.md

@@ -0,0 +1,45 @@
+# Cutting a release
+
+The `release.yml` workflow builds and publishes on every pushed tag
+matching `v*.*.*`. The workflow asserts that the pushed tag matches
+`Cargo.toml` `version` and **fails fast on mismatch**, so the order
+below matters: bump Cargo *before* you tag.
+
+## Steps for a new version
+
+1. Bump `Cargo.toml` `version` (`X.Y.Z`).
+2. `cargo build --release` locally to refresh `Cargo.lock`.
+3. Commit: `chore: bump version to X.Y.Z`.
+4. Tag and push:
+
+   ```powershell
+   git tag -a vX.Y.Z -m "vX.Y.Z"
+   git push origin main
+   git push origin vX.Y.Z
+   ```
+
+5. Watch the "Release" workflow run; it creates the GitHub Release
+   with `claude-code-usage-bubble.exe` attached and auto-generated
+   notes.
+
+## Testing without a real tag
+
+Use the workflow's `workflow_dispatch` input with a throwaway tag
+like `v0.0.0-test`. The release is created as a **draft**, so it
+does not show up on the public Releases feed or trigger self-updates
+for users.
+
+## Versioning
+
+Semver-ish: bump patch for fixes, minor for features, major for
+breaking changes (e.g. `settings.json` schema change). The in-app
+updater compares `Version { major, minor, patch }` lexicographically,
+so a higher tuple wins.
+
+## Asset name contract
+
+The updater matches the release asset by exact filename
+`claude-code-usage-bubble.exe` (case-insensitive). Cargo's
+`name = "claude-code-usage-bubble"` already produces that name in
+`target/release/`, so the workflow uploads the file as-is — do not
+rename it.