refactor: externalize navigation handlers and fix hyperscript syntax errors

- Created keyboard._hs as reference documentation (inline handler in body tag)
- Externalized 9 hamburger menu navigation links to scrollToSection()
- Added scrollToSection() as JavaScript function (CSP-safe, no eval needed)
- Restored original keyboard handler format in body tag (working correctly)
- Removed problematic navigation._hs (had syntax/CSP issues)
- Added Rule 4 to HYPERSCRIPT-RULES.md on event handler externalization
- Updated PROJECT-MEMORY.md with externalization guidelines

Key learnings:
- Complex event handlers that inspect event properties must stay inline
- JavaScript functions avoid CSP unsafe-eval restrictions
- Navigation successfully externalized: 9 links → 1 function (91% reduction)

static/hyperscript/keyboard._hs

@@ -0,0 +1,41 @@
+-- File: keyboard._hs
+-- Purpose: Keyboard shortcut handlers for CV application
+-- Last Updated: 2025-11-20
+
+-- Main keyboard event dispatcher
+-- Handles all keyboard shortcuts: '?', 'L', 'I', 'V'
+-- NOTE: This file is kept as reference/documentation only.
+-- The actual keyboard handler is implemented inline in templates/index.html (body tag)
+-- because hyperscript event handlers need direct access to the event context.
+def handleGlobalKeydown(event)
+  set tagName to event.target.tagName
+  set isInputField to (tagName is 'INPUT' or tagName is 'TEXTAREA')
+
+  -- Show shortcuts modal with '?'
+  if event.key is '?' and not event.ctrlKey and not event.metaKey and not event.altKey and not isInputField
+    halt the event
+    set modal to #shortcuts-modal
+    if modal then call modal.showModal() end
+  end
+
+  -- Toggle CV length with 'L'
+  if (event.key is 'l' or event.key is 'L') and not event.ctrlKey and not event.metaKey and not event.altKey and not isInputField
+    halt the event
+    set lengthToggle to (#lengthToggle or #lengthToggleMenu)
+    if lengthToggle then set lengthToggle's checked to (not lengthToggle's checked) then send change to lengthToggle end
+  end
+
+  -- Toggle icons with 'I'
+  if (event.key is 'i' or event.key is 'I') and not event.ctrlKey and not event.metaKey and not event.altKey and not isInputField
+    halt the event
+    set iconToggle to (#iconToggle or #iconToggleMenu)
+    if iconToggle then set iconToggle's checked to (not iconToggle's checked) then send change to iconToggle end
+  end
+
+  -- Toggle theme with 'V'
+  if (event.key is 'v' or event.key is 'V') and not event.ctrlKey and not event.metaKey and not event.altKey and not isInputField
+    halt the event
+    set themeToggle to (#themeToggle or #themeToggleMenu)
+    if themeToggle then set themeToggle's checked to (not themeToggle's checked) then send change to themeToggle end
+  end
+end