Add Matrix sync state handling

[mdheller]

Summary

Adds durable Matrix sync state handling and room resolution for AgentTerm Matrix workflows.

This PR adds:

• matrix_state.py with MatrixSyncState, MatrixStateStore, room resolution, and room extraction from sync payloads.
• agent-term-matrix --state option.
• agent-term-matrix state command.
• normalize-sync --save-state to persist next_batch and joined room IDs.
• Room key/alias resolution for agent-term-matrix send using Matrix config and durable state.
• Tests for Matrix state persistence, next-batch updates, room extraction, room resolution, config-driven send room resolution, state-saving sync normalization, and state display.

Boundary decisions

• This is local durable sync state, not a live homeserver sync loop yet.
• Matrix sends still route through dispatch and remain Policy Fabric-gated.
• Sensitive sends remain E2EE posture-gated.
• Access tokens still remain outside JSON config.
• Live incremental /sync I/O remains a follow-up lane behind the Matrix service backend.

Validation

Expected CI:

ruff check .
pytest

Next lane after merge: live incremental Matrix sync command that uses stored next_batch and the optional matrix-nio backend.