Add route interactions: click-to-split, drag-to-reshape, colored route rendering

- Enrich BRouter response with per-point 3D coordinates and segment boundary
  tracking (EnrichedRoute interface)
- ColoredRoute component: plain, elevation gradient (green→yellow→red), and
  surface color modes with invisible wide polyline for click targeting
- Click-to-split: click on route polyline inserts waypoint at nearest point,
  mapped to correct segment via boundary indices
- MidpointHandles: draggable CircleMarkers at route segment midpoints for
  reshaping, hidden below zoom 12, opaque on hover
- Color mode toggle (select) synced via Yjs routeData
- i18n keys for color mode labels (en + de)
- Unit tests for segment boundary tracking (13 tests)
- E2E tests for enriched route response and color mode toggle

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

openspec/specs/transactional-emails/spec.md

@@ -0,0 +1,44 @@
+## Requirements
+
+### Requirement: Email sending interface
+The system SHALL provide a provider-agnostic email sending function that supports HTML and plain-text content.
+
+#### Scenario: Send email in production
+- **WHEN** the system sends a transactional email in production
+- **THEN** the email is delivered via the configured provider (Resend) to the recipient
+
+#### Scenario: Dev mode skips sending
+- **WHEN** the system sends a transactional email in development
+- **THEN** the email content is logged to console and no external API is called
+
+### Requirement: Magic link email
+The system SHALL send an email containing the magic link when a user requests passwordless login.
+
+#### Scenario: Magic link delivered
+- **WHEN** a user requests a magic link login
+- **THEN** an email is sent with a clickable link that logs them in
+
+#### Scenario: Email content
+- **WHEN** a magic link email is sent
+- **THEN** it includes: the link, expiry time (15 minutes), and plain-text fallback
+
+### Requirement: Welcome email
+The system SHALL send a welcome email after successful registration.
+
+#### Scenario: Welcome on registration
+- **WHEN** a user completes passkey registration
+- **THEN** a welcome email is sent to their registered email address
+
+### Requirement: Email templates
+Each email type SHALL have an HTML template with a plain-text fallback.
+
+#### Scenario: Extensible template pattern
+- **WHEN** a new email type is needed in the future
+- **THEN** it can be added by creating a template function and calling sendEmail
+
+### Requirement: Privacy disclosure
+Email sending SHALL be documented in the privacy manifest.
+
+#### Scenario: Privacy manifest updated
+- **WHEN** transactional emails are enabled
+- **THEN** the /privacy page documents: what emails are sent, that email addresses are shared with the email provider, and which provider is used