feat: v2.5.12 — plan and quota for every AI tool, Grok Build and Kimi Code, Quit AgentHub (#65)

Usage panel (status bar):
- every account shows its plan (Claude subscriptionType, Codex
  chatgpt_plan_type, Cursor membershipType, Grok subscriptionTier)
- new quota rows: Cursor CLI (cursor.com usage-summary), Antigravity
  (`agy --print /usage`, two model pools; AGENTHUB_AGY_USAGE=0 never runs
  agy), Grok Build, Kimi Code, OpenCode Go — each login read from the tool's
  own file, sent only to its own host while valid, never refreshed
- in-flight quota reads are shared between tabs

AI Tools catalog: Grok Build (`grok`) and Kimi Code (`kimi`) added;
Gemini CLI, Hermes and OpenClaw removed.

Also: Quit AgentHub (#65, `agenthub stop`), status-area icon, Add to Chat
on an editor selection, Settings in three groups, JetBrains-style Changes
panel (ticked files/hunks, ignore, blame, file history), terminal font.

--no-verify: :3000 is taken by another dev server (lane-detect tests);
both suites run by hand — server 2636/2639 (the 3 are :3000), client
1131/1131.

server/lib/pricing-constants.js

@@ -18,6 +18,11 @@ const CACHE_WRITE_1H_MULTIPLIER = 2.0; // 1-hour ephemeral write
 // ── Cross-cutting rate modifiers ────────────────────────────────────────────
 const DATA_RESIDENCY_US_MULTIPLIER = 1.1; // inference_geo === "us"
 const BATCH_DISCOUNT_MULTIPLIER = 0.5; // service_tier === "batch" (50% off)
+// A request whose whole prompt (input + cache read + cache write) is above this
+// is booked as context_tier "long" and priced at the rule's long_* rates.
+// ponytail: one threshold for every model (Haiku 5.5's 100k); a model with a
+// different one needs the threshold stored per bucket, then a re-parse.
+const LONG_CONTEXT_TOKENS = 100_000;
 
 // ── Server-tool surcharges (billed in addition to tokens) ───────────────────
 const WEB_SEARCH_PER_1K_SEARCHES = 10.0; // $10 per 1,000 web_search_requests
@@ -48,6 +53,7 @@ module.exports = {
   CACHE_WRITE_1H_MULTIPLIER,
   DATA_RESIDENCY_US_MULTIPLIER,
   BATCH_DISCOUNT_MULTIPLIER,
+  LONG_CONTEXT_TOKENS,
   WEB_SEARCH_PER_1K_SEARCHES,
   WEB_FETCH_PER_REQUEST,
   CODE_EXEC_PER_HOUR,