Extract ContextCompressor, fix STL viewer, expand test suite, add architecture audit docs ...

- Extract ContextCompressor from agent.py (Step 1 of god-object refactor)
- Add retry + hard-truncate fallback logic to ContextCompressor
- Add unit tests: agent loop (14), compressor (18), KV store (8),
  auth encrypt (3), auth deps (13), todo/scratchpad/image_view/memory
- Fix WebGL STL viewer: allow-same-origin sandbox + graceful fallback
- Add CompressionStarted event and client-side compression notice
- Add docs/architecture_weak_spots.md and plan_01_god_object_agent.md
- Update test_events.py and test_agent_context_size.py for new logic

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

Add self-recall (scheduled callback) system ...

Core features:
- schedule_recall tool: once/recurring/immediate callbacks
- manage_recall tool: cancel/skip/list scheduled recalls
- Natural-language time parser (ISO, relative, "tomorrow at 09:00")
- PostgreSQL-backed RecallScheduler with lazy pool init
- Background recall_scheduler_loop with asyncio.Semaphore(3)
- _busy_sessions guard prevents user messages during headless runs
- Agent.run() preserves thinking field for session history visibility
- API endpoints: GET/DELETE/POST for session recall, admin list
- Frontend: recall badge, filter, cancel/skip in sidebar and chat header
- Tests: parser, scheduler CRUD, tools, API, scheduler loop (53 tests)
- Manuals: schedule_recall.md and manage_recall.md

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

Phase 2 — Memory store + extractor unit tests ...

- tests/conftest_factory.py: add FakeRecord, FakeConnection, FakePool, make_store_with_pool
- tests/unit/memory/test_store.py: 18 tests for upsert, vector/ILIKE search, delete, list, count, summary, session state, backfill
- tests/unit/memory/test_extractor.py: 11 tests for JSON extraction, invalid JSON, empty response, tool result truncation, summary regeneration
- docs/testing.md: update coverage status, add FakePool usage example

88 total tests passing (59 + 29).

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

Bootstrap test suite — Phase 1 unit tests ...

- docs/testing.md: testing strategy, mock strategy, phase breakdown
- tests/conftest.py: autouse fixture to reset navi.config.settings per test
- tests/conftest_factory.py: FakeLLMBackend, FakeTool, make_profile, make_registry helpers
- tests/unit/core/test_events.py: wire serialization for all 15 event dataclasses
- tests/unit/core/test_compressor.py: should_compress, partition_messages, format_for_summary, compress_context
- tests/unit/core/test_registry.py: ToolRegistry, ProfileRegistry, BackendRegistry
- tests/unit/core/test_context_builder.py: system prompt caching, persona injection, goal anchor, iteration budget
- tests/unit/profiles/test_base.py: Pydantic model coercion, defaults, extra fields
- navi/core/context_builder.py: use module-level `import navi.config` instead of `from navi.config import settings` so tests can swap the singleton

59 tests passing.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>