docs: Foundation Freeze v1.0 complete + Experience Audit + Core Principle Check

- FOUNDATIONS-v1.0.md updated:
  - Added Landvex Core Principle and Design Constitution to frozen foundations
  - Added Core Principle Rules to invariants (2.4)
  - Reordered component priority: Modal, Search, Map Panel, Navigation, Table, Data Grid
  - Reflects business value: search and maps are central to Landvex

- EXPERIENCE_AUDIT.md (v1.0, LOCKED):
  - Four questions for every screen:
    1. Can purpose be understood in 3 seconds?
    2. Is 'Reality → Decision' visible?
    3. Is it obvious what the user should do?
    4. Does everything contribute to the decision?
  - Three-second rule levels with verification method
  - Audit process: select screens → apply questions → prioritize fixes → verify
  - Example audit format
  - Core Principle Check for RFCs: 4 questions before approval

- COMPONENT_TEMPLATE.md updated:
  - Added Core Principle section to template
  - Requires: decision support, cognitive load reduction, 3-second understanding

- RFC_DEFINITION_OF_DONE.md updated:
  - Added Core Principle as criterion #2 (was 12 criteria, now 13)
  - Exit criteria: must pass all 13

Rationale: Freeze foundation with Core Principle as highest authority.
Experience audit ensures all screens support decision-making.
Core Principle Check prevents components that don't serve the user.
Business-value prioritization: search and maps before tables.

docs/design/foundations/COMPONENT_TEMPLATE.md

@@ -22,6 +22,11 @@ Copy this template for each new component. Remove sections that do not apply. Ad
 
 **Design Goal:** One sentence describing the ideal user experience.
 
+**Core Principle:** How does this component support "From Reality → Decision"?
+- What decision does it help the user make?
+- How does it reduce cognitive load?
+- Can it be understood in 3 seconds?
+
 **Tier:** [1 (Canonical) / 2 (Derived) / 3 (Domain)]
 
 **Inherits From:** [Parent component, or "—" if canonical]