Pass explicit ToolContext to tools instead of hidden ContextVars ...

Add ToolContext dataclass (session_id, event_sink, stop_event, model,
user_id, user_role, user_info) and thread it through the execution chain:
Agent._execute_tools_with_sink → ToolExecutor → tool.execute().

All ~25 tools updated to accept ctx parameter. Tools that previously
read ContextVar now prefer ctx when provided, falling back to
ContextVar for backward compatibility.

Tests updated to pass ToolContext explicitly — no more test fixtures
that set current_session_id / current_user_id ContextVars.

ContextVar setters remain as fallback for non-tool consumers
(ai_helper, context_builder, planning) and will be removed in a
follow-up refactor.

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

Refactor: move tool helper modules into _internal subpackage ...

Moves non-tool infrastructure out of navi/tools/ root so that only
actual tool classes live there:

  base.py           → _internal/base.py
  loader.py         → _internal/loader.py
  middleware.py     → _internal/middleware.py
  logging_middleware.py → _internal/logging_middleware.py
  _time_parser.py   → _internal/time_parser.py

All imports updated across core/, api/, mcp/, tools/, and tests/.
No proxy files remain in navi/tools/ root.

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

Clarify knowledge persistence prompts

Tune reflect autonomy guidance

reflect: force clarification when Detailer finds strategic ambiguity ...

Closing instruction now explicitly requires stopping to ask the user
if the Detailer identified ambiguities about core direction (what to
build, which approach, what the user actually wants). Prevents Navi
from using the Pragmatist's simplifications as an escape hatch when
the real problem is underspecified requirements.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

Add reflect tool: three parallel expert perspectives ...

ReflectTool runs Critic / Pragmatist / Detailer advisors concurrently
via asyncio.gather() + AIHelper.ask(). Each role has a distinct system
prompt designed to produce genuinely different analysis:
- Critic: challenges assumptions, surfaces risks and logical gaps
- Pragmatist: finds the simplest path, cuts unnecessary complexity
- Detailer: spots missing requirements, edge cases, ambiguities

Parameters: situation (required), assumptions (required list — the key
input that forces Navi to surface implicit beliefs), tried (optional).

Registered as a builtin with AIHelper injection. Added to all three
profiles. Persona updated with guidance on when to use it (complex or
ambiguous tasks before planning, or when stuck mid-execution).

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>