feat(frontend): add dedicated /cli page, nav links, and CTA buttons; remove CLI modals for leaner UX

- New CLI page at /cli with detailed usage and improved Quick Start card header
- Add CLI link to navbars and small ‘Try the CLI’ CTAs on Home & Templates
- Remove CLI modals and unused showCliModal() handler (keep_small_simple)
- Self-host Bootstrap and Font Awesome; add OSI logo and GPL notice in footers
- Dockerfile: verify vendor assets exist at build time
- Minor a11y/contrast and heading-order cleanups (100 a11y)

frontend/static/img/osi-logo.svg

@@ -0,0 +1,34 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<svg
+  xmlns="http://www.w3.org/2000/svg"
+  width="128"
+  height="128"
+  viewBox="0 0 128 128"
+  role="img"
+  aria-labelledby="title desc">
+  <title id="title">Open Source Initiative (OSI) Logo</title>
+  <desc id="desc">Green circular mark with a keyhole-shaped cutout representing the Open Source Initiative.</desc>
+  <!--
+    This is a simplified vector rendition of the OSI "Open Source" mark.
+    The OSI logo is a trademark of the Open Source Initiative.
+    See https://opensource.org/trademark for usage guidelines.
+  -->
+  <defs>
+    <mask id="osi-cutout" maskUnits="userSpaceOnUse">
+      <!-- Start fully transparent -->
+      <rect x="0" y="0" width="128" height="128" fill="black"/>
+      <!-- Keep the outer circle area -->
+      <circle cx="64" cy="64" r="60" fill="white"/>
+      <!-- Cut out inner circle (keyhole top) -->
+      <circle cx="64" cy="64" r="26" fill="black"/>
+      <!-- Cut out the keyhole stem; rounded for a smooth shape -->
+      <rect x="53" y="86" width="22" height="30" rx="6" ry="6" fill="black"/>
+    </mask>
+  </defs>
+
+  <!-- Apply the mask to a solid green rectangle -->
+  <rect x="0" y="0" width="128" height="128" fill="#3DA639" mask="url(#osi-cutout)"/>
+
+  <!-- Optional subtle outline for crisp edges on various backgrounds -->
+  <circle cx="64" cy="64" r="60" fill="none" stroke="#2a7a2a" stroke-width="1" opacity="0.5"/>
+</svg>