refactor: use idiomatic hyperscript selector syntax

Replace verbose document.getElementById() and document.querySelectorAll()
with cleaner hyperscript syntax:
- #id for ID selectors
- .class and the first .class for class selectors
- <selector/> query literals for complex selectors
- #{variable} for dynamic ID interpolation

Files changed:
- utils._hs: scrollHeight, details, footer buttons, scrollToSection
- zoom._hs: all zoom control element selectors (14 changes)
- pdf-modal._hs: modal selector
- keyboard._hs: dynamic toggle and modal selectors
- contact-modal.html: response div and modal close
- index.html: ninja-keys bar selector

templates/index.html

@@ -6,7 +6,7 @@
          on scroll from window call handleScroll()
          on keydown
            set tag to event.target.tagName
-           set ninjaKeys to document.getElementById('cmd-k-bar')
+           set ninjaKeys to #cmd-k-bar
            set ninjaOpen to (ninjaKeys is not null and ninjaKeys.opened)
            set skip to (tag is 'INPUT' or tag is 'TEXTAREA' or ninjaOpen)
            set noMod to (not event.ctrlKey and not event.metaKey and not event.altKey)

templates/partials/modals/contact-modal.html

@@ -29,7 +29,7 @@
                   hx-headers='{"X-Requested-With": "XMLHttpRequest"}'
                   _="on htmx:afterRequest
                        -- Check if response contains success message (not validation error)
-                       set responseDiv to document.getElementById('contact-response')
+                       set responseDiv to #contact-response
                        if responseDiv is not null and responseDiv.querySelector('.contact-success') is not null
                          -- Hide all form fields and show only success message
                          set formFields to me.querySelectorAll('.form-group')
@@ -39,7 +39,7 @@
                          add .hidden to me.querySelector('.form-actions')
                          add .hidden to me.querySelector('.form-note')
                          -- Close modal after 3 seconds
-                         wait 3s then call document.getElementById('contact-modal').close()
+                         wait 3s then call #contact-modal.close()
                        end">
 
                 <!-- Honeypot field - hidden, should be empty -->