Stage 3/3: Wire agy/Flash to the MCP server + end-to-end verify (completes #73)

[JoshuaVSherman]

Part of #73 (see it for full inventory, architecture, and rationale). Depends on Stage 2 (the MCP server). This is the completing stage — its PR closes the epic #73.

Stage 3 of 3 — Wire agy/Flash to the MCP server + end-to-end verify

Connect agy to the shared MCP server so Gemini Flash can complete tool-bound tasks end-to-end, with no OMEN-desktop dependency.

The change

• Add the server to agy's MCP config at ~/.gemini/config/mcp_config.json (mcpServers entry: command / args / env).
• Confirm Flash can discover and call the tools mid-session (so it can write copy AND perform the tool action — e.g. draft the venue email then gmail_draft_email — in one task).

Acceptance criteria

• agy/Flash lists the 17 tools from the MCP server.
• Flash completes a real gig-promo task end-to-end (copy + tool action) in a single session, no desktop/Gemma needed.
• Human-in-the-loop preserved (drafts staged, protected files blocked).
• Gemma still works as fallback consuming the same core (regression check across the whole chain).
• Docs/README note the shared-core + MCP setup for future consumers (incl. Claude Code).

PR closing keyword: this completing PR uses Closes #<this issue> AND Closes #73 (epic).