chore: touch up docs

[sagar-kap]

Description

Brings the README and docs site in line with the now-shipped v0.1.2
binary release: real install instructions, a mascot, brand-consistent
favicon and header logo, and Umami analytics wired up the same way
tech.weburz.com does it. No code changes — purely docs, branding, and
client-side analytics scaffolding.

Modifications

• README.md — added a row of five brand-themed status badges
  (Release, License, Go Version, QA Checks, Go Report Card — all
  styled in burzyellow / burzblue-950 to match the rest of the
  visual identity) and the mascot image as a hero, placed directly
  under the H1.
• assets/goterox.png (new) — the Terox mascot: a Go gopher in a
  hard hat assembling scaffolding around translucent template files
  with {{.variable}} tokens floating around. Lives at the repo root
  under assets/ so the README renders it on GitHub via a relative
  path.
• docs/public/goterox.png (new) — exact mirror of the same
  image so Nuxt can serve it at /goterox.png for the docs site.
  Two copies is intentional: avoids symlink fragility and lets each
  renderer (GitHub vs. Nuxt) resolve the path from its own root.
• docs/public/favicon.svg (new) — 64×64 SVG favicon: rounded
  burzyellow-500 square with a chunky filled burzblue-950 "T".
  Pure brand colors, no external assets.
• docs/nuxt.config.ts — registered the new favicon via
  app.head.link, and added runtimeConfig.public.umamiWebsiteId: ""
  so the Umami plugin can pick up the website ID from the
  NUXT_PUBLIC_UMAMI_WEBSITE_ID env var at runtime.
• docs/app/components/AppLogo.vue — replaced the old
  stroke-based "T" with a single solid filled path so the header
  logo visually matches the new favicon at every size. Same 32×32
  viewBox, same design-system color tokens (fill-primary-500,
  fill-neutral-900) so future brand tweaks flow through
  automatically.
• docs/app/plugins/umami.client.ts (new) — Nuxt client-only
  plugin that injects the https://umami.weburz.com/script.js tag
  when umamiWebsiteId is set. Direct mirror of the
  tech.weburz.com pattern. The .client.ts suffix keeps it out of
  SSR; the empty-string default in runtime config means analytics
  stays off in local pnpm dev and only activates when the env var
  is set in the deployment.
• docs/content/1.getting-started/1.introduction.md — embedded
  the mascot at the top of the introduction page so first-time
  visitors are greeted by the gopher before any prose.
• docs/content/1.getting-started/2.installation.md — rewrote
  the page now that v0.1.2 actually ships binaries. Leads with
  Homebrew (macOS/Linux) and Scoop (Windows), then direct binary
  download with a checksum mention, then go install demoted to a
  "for Go developers" section, then "build from source" preserved.
  Added an "Updating" table mapping each install method to its
  update command. Removed the "prebuilt binaries — Not yet shipping"
  callout that was no longer true. Frontmatter description updated
  to match the new reality.