Add plugin entries: omniroute-acp, antigravity-acp

[nuchareviews-beep]

What these plugins do

• omniroute-acp — registers a local OmniRoute instance as a BB agent provider (turns forwarded to its OpenAI-compatible /api/v1/chat/completions), exposes its usage/cost metrics via this plugin's own RPC, and adds an omniswarm_spawn native tool for fanning tasks out to parallel hidden subagent threads.
• antigravity-acp — registers the local Antigravity CLI (agy) as a BB agent provider by shelling out to it per turn, with best-effort session continuity via agy --conversation.

Both are single-shot, non-streaming bridges (documented as a known limitation in each README) — sufficient to route chat completions through each backend end-to-end, not a full-featured streaming/tool-calling bridge yet.

Source release

• omniroute-acp → https://github.com/nuchareviews-beep/bb-plugin-omniroute-acp.git, range ^0.1.0, tag v0.1.0 (commit c186c34)
• antigravity-acp → https://github.com/nuchareviews-beep/bb-plugin-antigravity-acp.git, range ^0.1.0, tag v0.1.0 (commit cb92a8c)

Both tags are pushed and confirmed live via git ls-remote --tags.

Plugin checks

• bb plugin build succeeds for both (server + host artifacts).
• Both were run against real live systems before this submission: omniroute-acp completed a real thread turn through a live OmniRoute instance (/api/v1/chat/completions); antigravity-acp completed a real thread turn by shelling out to a real agy CLI session.

Marketplace checks

• npm ci && npm run build — succeeds, composes 65 entries including both new ones.
• npm run check — succeeds; the liveness check resolved both ^0.1.0 ranges against the live tags above.
• No icon files vendored — both entries use the Zap host icon name (matches each plugin's own bb.branding.icon; neither has custom artwork yet).

Permissions / external services

• omniroute-acp calls out to whatever OmniRoute base URL the user configures (default http://localhost:20128) and stores an optional API key as a plugin secret.
• antigravity-acp shells out to a locally-installed agy binary; no network calls originate from the plugin itself beyond what agy does on its own.
• Neither plugin is a first-party/reviewed publisher; source and behavior are as described in each README, open to review.