Add Starlight docs for v3.02 signal monitoring and RF analysis tools

New pages (Diátaxis framework):
- tools/skywalker.mdx: reference for all 5 skywalker.py modes
- tools/spectrum-analysis.mdx: how-to guide for RF analysis workflows
- hardware/rf-coverage.mdx: explanation of LNB shifting and L-band coverage

Updated pages:
- firmware/custom-v301.mdx: v3.02 commands (0xB7-0xB9) with protocol docs
- usb/vendor-commands.mdx: signal monitoring command reference
- astro.config.mjs: sidebar entries and firmware version label

site/astro.config.mjs

@@ -29,6 +29,7 @@ export default defineConfig({
             { label: 'Overview', slug: 'hardware/overview' },
             { label: 'GPIO Pin Map', slug: 'hardware/gpio-pinmap' },
             { label: 'RF Specifications', slug: 'hardware/rf-specifications' },
+            { label: 'RF Coverage', slug: 'hardware/rf-coverage' },
           ],
         },
         {
@@ -77,7 +78,7 @@ export default defineConfig({
             { label: 'Rev.2 Analysis', slug: 'firmware/rev2-analysis' },
             { label: 'Kernel FW01', slug: 'firmware/kernel-fw01' },
             { label: 'FW2.13 Variants', slug: 'firmware/fw213-variants' },
-            { label: 'Custom v3.01', slug: 'firmware/custom-v301' },
+            { label: 'Custom v3.01\u2013v3.02', slug: 'firmware/custom-v301' },
             { label: 'Storage Formats', slug: 'firmware/storage-formats' },
           ],
         },
@@ -93,9 +94,11 @@ export default defineConfig({
           items: [
             { label: 'Firmware Loader', slug: 'tools/firmware-loader' },
             { label: 'Tuning', slug: 'tools/tuning' },
+            { label: 'SkyWalker RF Tool', slug: 'tools/skywalker' },
             { label: 'EEPROM Utilities', slug: 'tools/eeprom-utilities' },
             { label: 'Debugging', slug: 'tools/debugging' },
             { label: 'TS Analyzer', slug: 'tools/ts-analyzer' },
+            { label: 'Spectrum Analysis', slug: 'tools/spectrum-analysis' },
           ],
         },
         {