feat(achievements): share card render on unlocked badges (#19657)

* feat(achievements): share card render on unlocked badges

Adds a Share button to each unlocked achievement card that opens a
modal and renders a 1200x630 PNG share card client-side via Canvas2D
(no backend, no network, no new deps). Two actions: Download PNG and
Copy image to clipboard.

Card layout mirrors the in-dashboard visual language: tier-colored
glow, icon from the existing LUCIDE sprite set, achievement name,
tier badge pill, description, progress stat line, and a Hermes Agent
watermark. Sized for X/Twitter, Discord, LinkedIn, Bluesky link
previews.

Vendored on top of the upstream @PCinkusz bundle; the 'in-progress
scan banner' precedent already established this divergence pattern.
Manifest bumped 0.3.1 -> 0.4.0.

* feat(achievements): share-on-X as primary action on share dialog

Adds a 'Share on X' button as the primary action in the share dialog.
Opens https://x.com/intent/post with a pre-filled tweet referencing
the achievement name, tier, @NousResearch, and the Hermes docs URL.
Copy image and Download PNG become secondary actions: users who want
the badge attached can Copy image, paste into the X composer, post.

Primary button styled as X's signature black-on-white fill so the
action is unambiguous.

plugins/hermes-achievements/dashboard/manifest.json

@@ -3,7 +3,7 @@
   "label": "Achievements",
   "description": "Steam-style achievements for vibe coding and agentic Hermes workflows.",
   "icon": "Star",
-  "version": "0.3.1",
+  "version": "0.4.0",
   "tab": { "path": "/achievements", "position": "after:analytics" },
   "entry": "dist/index.js",
   "css": "dist/style.css",