items 5-7: passkey step-up, tools enable/disable, note RAG — end to end

Completes the three in-flight open items and fixes the away-fallthrough bug.

Item 7 — passkey step-up (WebAuthn):
- internal/webauthn: ES256/P-256 register + assert with real ecdsa signature
  verification, minimal CBOR/COSE decode, PasskeySession (L2→L3 on assert,
  decays after TTL). Drop the RS256 offer we can't verify (register-ok/
  assert-fail trap). Verify rpIdHash + UP/UV flags in FinishAssertion — UV is
  the step-up gesture. Round-trip test with negative cases (tampered sig,
  missing UV, wrong origin).
- cmd/mavweb: /auth/passkey enroll+assert page (the only surface that can do
  a WebAuthn gesture) + the four begin/finish endpoints. Without this the
  daemon's PasskeySession swap leaves /tools enable permanently blocked.
- daemon wires PasskeySession as the auth Session + srv.StepUp; policy gates
  MethodAssertStepUp at AuthRead.

Item 5 — tools page: DisableTool through store/ipc/client/wire; /tools grows a
disable action and a link to the passkey page. Lifecycle test.

Item 6 — note RAG: PhraseQuery on the phraser (LLM-composed answer over top-k
notes, raw-notes fallback); IntentQuery routes through it. Stub returns a
deterministic summary.

Item 2 — away-fallthrough: on ErrVoiceNoSession the dispatcher now reroutes
through the AWAY table (sev3→ntfy, sev4→telegram-repeat-til-ack, sev≤2→drop)
instead of silently dropping / mis-routing to the present-list remainder.
Covers DispatchNudge + DispatchReminder. 4 tests.

Also: re-add ProposeTool to CoreAPI (dropped in a comment rewrite), fix
missing imports + a duplicate block left mid-edit, drop dead AssertStepUpFunc,
gitignore /mavcaldav.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

internal/webauthn/session.go

@@ -0,0 +1,60 @@
+package webauthn
+
+import (
+	"context"
+	"fmt"
+	"sync"
+	"time"
+
+	"github.com/kami/maven/internal/auth"
+)
+
+// PasskeySession implements auth.Session backed by WebAuthn passkey assertion.
+// The session starts at Layer2 (passkey is enrolled, this session exists) and
+// bumps to Layer3 on successful Assert(), which lasts for assertionTTL before
+// decaying back to Layer2.
+//
+// A nil *PasskeySession is a valid zero: it acts like a session with no
+// credentials enrolled (always L2, Assert returns ErrStepUpUnsupported).
+// This mirrors the FloorSession behavior when passkey is not configured.
+type PasskeySession struct {
+	mu           sync.Mutex
+	assertedAt   time.Time // zero = not asserted this session
+	assertionTTL time.Duration
+}
+
+// NewPasskeySession creates a session. The caller chooses the assertion TTL
+// (how long a step-up gesture remains valid). 5 minutes is a sensible default.
+func NewPasskeySession(assertionTTL time.Duration) *PasskeySession {
+	if assertionTTL <= 0 {
+		assertionTTL = 5 * time.Minute
+	}
+	return &PasskeySession{assertionTTL: assertionTTL}
+}
+
+// CurrentLayer returns L3 if step-up has been asserted within the TTL,
+// otherwise L2 (passkey enrolled, this session proven). A nil receiver
+// returns L2 (no way to reach L3 without a session).
+func (s *PasskeySession) CurrentLayer(_ context.Context, _ auth.Scope) auth.Layer {
+	if s == nil {
+		return auth.Layer2
+	}
+	s.mu.Lock()
+	defer s.mu.Unlock()
+	if !s.assertedAt.IsZero() && time.Since(s.assertedAt) < s.assertionTTL {
+		return auth.Layer3
+	}
+	return auth.Layer2
+}
+
+// Assert records a successful step-up gesture. The session bumps to L3 for
+// the assertion TTL. A nil receiver returns ErrStepUpUnsupported.
+func (s *PasskeySession) Assert(_ context.Context, _ auth.Scope) error {
+	if s == nil {
+		return fmt.Errorf("%w: passkey session not configured", auth.ErrStepUpUnsupported)
+	}
+	s.mu.Lock()
+	defer s.mu.Unlock()
+	s.assertedAt = time.Now()
+	return nil
+}