fix(matrix): make auto_accept_invites configurable, default to false

[Reaster0]

Summary

• MatrixAdapter hardcoded auto_accept_invites: true, meaning any Matrix-connected instance would blindly join every room it was invited to
• This is a security concern for public-facing homeservers — a malicious user could invite the bot into an arbitrary room and interact with the agent without the operator's consent
• The field was not exposed in MatrixConfig, so operators had no way to disable it

Changes

• Add auto_accept_invites: bool to MatrixConfig (openfang-types), with #[serde(default)] defaulting to false
• Thread the field through MatrixAdapter::new() instead of hardcoding true
• Wire it in channel_bridge.rs from mx_config.auto_accept_invites
• Update unit tests to pass the new parameter

Migration

Breaking change in default behavior: existing setups that relied on auto-accept will need to explicitly opt in:

[channels.matrix]
auto_accept_invites = true

Test plan

• cargo build --workspace --lib compiles
• cargo test --workspace passes (3 updated test call sites in matrix.rs)
• Start daemon with auto_accept_invites = false (default) — invite the bot to a room, verify it does not join
• Set auto_accept_invites = true — invite again, verify auto-join works
• Verify allowed_rooms filtering still applies when auto-accept is enabled

🤖 Generated with Claude Code

[jaberjaber23]

Clean, minimal, security-positive change. Threads auto_accept_invites from config through channel_bridge to MatrixAdapter correctly. Default false is the right secure-by-default posture. Call chain verified complete. Tests updated.