feat: align production identity with legacy Buzz

[luispadron]

Add an opt-in production Tauri configuration matching legacy Buzz: Buzz.app, xyz.block.buzz.app, executable buzz-desktop, and macOS display metadata. Reuse the existing Block Developer ID signer and buzz:// scheme.

Resolve desktop plugin profiles under the selected app identity, preserving explicit home/profile overrides. Document the production build command and signing contract. Scheduled previews retain their current identity. Account migration and updater cutover are outside this PR.

Validated native compilation with both configurations, plist syntax, and identity values against legacy Buzz. Signed packaging and an installed-app upgrade remain untested.

Generated with Codex

[wesbillman]

Star Lord’s automated source review via Wes’s GitHub account.

One P1 integration finding, detailed inline: the production identity collides with the existing legacy-process handover guard. Please address it before using this overlay as the installed-app replacement. Non-blocking COMMENT only; not an approval or merge authorization.

Reviewed head 71dcf725e0c9a37ae790c381909c312e5ff483c2 against base/merge-base 4012979b1d200c3793714d7d7438e6dcd5231668: all six changed files plus plugin-manager initialization/CLI callers, agent Start/Restart/restore, credential namespace, deep links, release signing contract and notification presentation ownership. The opt-in overlay leaves the scheduled preview workflow unchanged; account migration and updater integration remain outside this PR.

Validation: 28 immutable source extracts verified against Git blobs; git diff --check passed for these pins. JSON/plist were parsed as data, and product/bundle identity and inherited deep-link values were compared with the cited legacy configuration at b65cff31a4c5f4a0af63952b60a21fd73195321a. The existing live checkout was clean at dbad6526346e7350c528280ccc5cf6c68e740607; it was not switched or modified. The finding is source-demonstrated, not an observed app run. No PR code, tests, builds, installers, app launches or credential operations were executed. CI was not assessed. Signed packaging, native runtime behavior and installed-app upgrade acceptance remain unverified.