feat: initial Greasy Sprocket website — Astro static + Go feedback service

- Astro 5.x static site with content collections for extensions
- Pages: index, [slug] (per-extension), coffee (Ko-fi), feedback form
- Go binary gs-feedback: SQLite storage + Discord webhook notification
- Nginx config: static serving + POST proxy to Go backend
- Deploy script: build + rsync to VPS
- ThockBoard landing page with features and sound pack listing

astro/src/content/extensions/thockboard.md

@@ -0,0 +1,39 @@
+---
+name: ThockBoard
+tagline: Mechanical keyboard sounds for every keystroke. 16 sound packs, zero setup.
+features:
+  - "16 sound packs (Cherry MX, buckling spring, zen, water drops, and more)"
+  - "Adjustable volume per pack"
+  - "Dark/light theme with palette switcher"
+  - "Works on any website — no configuration needed"
+  - "100% free, no premium tiers"
+screenshot: "/images/thockboard-preview.png"
+chromeStoreUrl: ""
+downloadUrl: "https://git.d0a1.es/d0a1/thockboard/releases"
+---
+
+ThockBoard adds satisfying mechanical keyboard sounds to every keystroke, on any website.
+
+Choose from 16 carefully crafted sound packs — from the classic Cherry MX Blue click
+to soothing zen water drops and bamboo chimes. Each pack is synthesized with DSP
+for realistic, non-repetitive audio.
+
+## Sound packs
+
+| Category | Packs |
+|----------|-------|
+| Mechanical | Cherry MX Blue, Cherry MX Red, Buckling Spring, Topre |
+| Thocky | Thocky Default, Deep Thock, Hall Effect |
+| Zen | Water Drop, Bamboo, Singing Bowl, Crystal |
+| Fun | Bubble, Soft Tap, Pop, Mechanical Click, Rain |
+
+## Privacy
+
+ThockBoard doesn't collect any data. No analytics, no tracking, no telemetry.
+Sound files are bundled with the extension — nothing is downloaded from external servers.
+
+## Free forever
+
+ThockBoard is 100% free. All 16 sound packs are available to everyone. There are no
+premium tiers, no locked features, no usage limits. If you enjoy it, you can
+[buy me a coffee](/coffee) — but there's zero pressure.