Enhancement: apc mcp sync should warn or filter by source_tool to prevent cross-tool server contamination

[FZ2000]

Summary

apc mcp sync has no mechanism to distinguish between MCP servers that should be synced globally vs. those that are tool-specific. It broadcasts everything to all target tools, which can cause misconfiguration and creates a sync feedback loop.

The Feedback Loop Problem

After running apc mcp sync --all:

1. All 6 cached MCP servers (originally from claude-code + cursor) get written to gemini-cli, windsurf, and github-copilot
2. Next apc collect reads those tools and now sees 6 MCP servers from each
3. The servers all look like they "belong" to those tools
4. Source attribution is lost (see issue Bug: MCP server source_tool is misattributed after deduplication when same server name exists in multiple tools #47)

There is no way to break this cycle without manually editing config files.

Requested Features

Option 1: --source filter flag

# Only sync servers that were originally collected from cursor
apc mcp sync --all --source cursor

# Only sync servers tagged for all tools (source_tool=shared)
apc mcp sync --all --source shared

Option 2: Confirmation of cross-tool spread

When syncing a server to a tool different from its source_tool, show a warning:

! test-claude-mcp was collected from claude-code — sync to gemini-cli? [y/N]

Option 3: Selective server targeting in MCP config

Allow tagging MCP servers with which tools they should be synced to:

{
  "name": "my-server",
  "source_tool": "cursor",
  "targets": ["cursor", "claude-code"]  // only sync to these
}

Environment

• macOS Darwin 25.2.0 (arm64)
• apc version 0.1.0

[forge-fz2000]

This has been addressed in PR #60 (fix(#47,#44): fix MCP source_tool attribution and cross-tool broadcast).

The _filter_mcp_for_tool() function added in that PR implements exactly this behaviour: by default, apc mcp sync only applies each server to the tool it originated from (source_tool == tool_name). The --all-sources flag restores the previous broadcast behaviour when explicitly requested.

Closing as resolved by PR #60.