feat: per-tool settings, persistent settings file, Codex and Antigravity sessions, tokens and hooks (#40 B, C1, C2, D)

Part B: Model Pricing, Hook Configuration and CLAUDE_HOME move from
Settings → Dashboard to the Claude Code tab's AgentHub sub-tab
(ClaudeAgentHubSettings.tsx); CODEX_HOME is editable in Codex → AgentHub.
A home that is or contains the OS home is refused (EBADHOME).

Settings persistence: dashboard-saved settings go to
~/.config/agenthub/settings.env (AGENTHUB_SETTINGS_FILE), outside the plugin
cache an update wipes. Load order: real env > the checkout's .env > that file.
The first CLAUDE_HOME change pins DASHBOARD_DATA_DIR so the DB stays put.

C1: codex-usage.js reads Codex rollout journals into sessions (new column
tool) and token_usage, tracked per file in codex_rollouts; forks deduped by
total vector, sub-agent threads folded into the root; pricing-sync also
prices OpenAI models; PricingSettings with a vendor filter.

C2: codex-hooks.js installs AgentHub's hooks into $CODEX_HOME/hooks.json on
a click, through a stable forwarder; Codex trust is never written. The hook
route creates tool='codex' sessions and folds sub-agent hooks into the root.

D: antigravity-usage.js reads agy's per-conversation SQLite files (tokens
from ModelUsageStats) into tool='antigravity' sessions; antigravity-hooks.js
installs the named hook `agenthub` (PreInvocation, PostToolUse, Stop — never
PreToolUse) into ~/.gemini/config/hooks.json; Settings → Antigravity tab;
Gemini pricing.

Whole-change review fixes: sameOriginGuard on both home PUTs, routers.missing
on a CLAUDE_HOME change, reset-pricing scope, GET /api/sessions?tool=,
clear-data covering the new tables, Codex child-thread events moving no
status, hooks owning status only while current, EFOREIGN for a forwarder
that is not ours, agy quiet window and turn rules, AGENTHUB_SETTINGS_FILE
honoured from .env.

Docs, OpenAPI and the CLAUDE.md marker updated. Server 2141, client 779.

server/openapi-extra/override-ops.js

@@ -1081,8 +1081,25 @@ const paths = {
       tags: ["Settings"],
       summary: "Reset pricing table to defaults",
       description:
-        "⚠ DESTRUCTIVE to pricing customizations. Deletes EVERY row in the model_pricing table and re-seeds it from the dashboard's built-in DEFAULT_PRICING list. Any custom rates or custom model patterns you added are permanently lost — there is no undo. Captured session/token data is untouched (only the pricing rules used to *compute* cost change). The response returns the full freshly-seeded pricing table.",
+        '⚠ DESTRUCTIVE to pricing customizations. Deletes EVERY row in the model_pricing table and re-seeds it from the dashboard\'s built-in DEFAULT_PRICING list. Any custom rates or custom model patterns you added are permanently lost — there is no undo. Captured session/token data is untouched (only the pricing rules used to *compute* cost change). The response returns the full freshly-seeded pricing table. With `{"scope": "claude"}` (the Claude Code tab\'s button) only `claude-…` rows are deleted and re-seeded; every other vendor\'s rows and custom patterns are kept.',
       operationId: "resetPricing",
+      requestBody: {
+        required: false,
+        content: {
+          "application/json": {
+            schema: {
+              type: "object",
+              properties: {
+                scope: {
+                  type: "string",
+                  enum: ["claude"],
+                  description: "Reset only `claude-…` rows. Omitted: every row.",
+                },
+              },
+            },
+          },
+        },
+      },
       responses: {
         200: {
           description: "Pricing defaults restored",