docs: persona-pack .zip import instructions are stale — app now rejects them in favor of buzz-team-snapshot v1

[justanotherkevin]

Summary

PERSONA_PACK_SPEC.md and examples/meadow-core/README.md document importing a team via a .zip persona pack through My Teams → Import. That path no longer works — the app now rejects .zip team files outright with:

Legacy team files are no longer supported. Export a buzz-team-snapshot v1 .team.json or .team.png instead.

Steps to reproduce

1. cd examples/meadow-core && zip -r meadow-core.zip meadow-core
2. In the desktop app, open Agent Teams (note: also renamed from "My Agents" in the current UI, another place the docs are behind) → Import
3. Select the zip
4. App shows the "Legacy team files are no longer supported" error instead of importing

Root cause

• desktop/src-tauri/src/commands/team_snapshot.rs explicitly detects and rejects ZIP-magic-byte files (ZIP_MAGIC_PREFIX) with a hardcoded LEGACY_TEAM_ERROR, pointing users to the new buzz-team-snapshot v1 format (.team.json / .team.png) instead.
• Per CHANGELOG.md, that format landed in feat(managed_agents): add buzz-team-snapshot v1 codec #1784/feat(desktop): add team snapshot sharing commands #1790 and has been touched as recently as fix(sharing): preserve agent/team snapshot tEXt chunks through media sanitization #2438 — this isn't a brand-new regression, the docs and example have just been stale for a while.
• The new TeamSnapshot format (desktop/src-tauri/src/managed_agents/team_snapshot.rs) is designed to be exported from an existing team inside the app, not hand-authored from .persona.md source files — so there's no direct drop-in replacement for "here's a portable pack directory a user can zip and import," which is what the docs currently promise.

Where the stale docs live

• crates/buzz-persona/PERSONA_PACK_SPEC.md — "Desktop App Import" section describes the .zip → My Teams → Import flow as current, and separately references a "future 'Install Pack' UI button" that also doesn't exist yet.
• examples/meadow-core/README.md — usage instructions say to use the "Install Pack" button, which isn't implemented, and don't mention the zip-import path being retired.

Proposed changes

• Update PERSONA_PACK_SPEC.md's "Desktop App Import" section to reflect that .zip persona-pack import for teams is retired, and either document the actual current path to get a multi-agent pack into the app, or mark the feature as not-yet-supported if there truly isn't one
• Update examples/meadow-core/README.md's usage instructions to match whatever the current supported import path is (drop the "Install Pack" button reference until it ships)
• Either implement a persona-pack-directory → buzz-team-snapshot v1 conversion path (CLI or in-app), or explicitly document that persona packs and team snapshots are two separate, non-interchangeable concepts today
• Audit other docs/examples for the same "My Agents" → "Agent Teams" naming drift, since that rename doesn't appear to be reflected everywhere either

Environment

• Found while running the app from a fresh local build off main, following the documented Quick Start / persona pack instructions as written