feat: corporate actions from the Stockbit session (stocks actions, stocks calendar)

`idx stocks actions SYM [--kind ...]`: one stock's cash and stock
dividends, bonus shares, rights, warrants, splits and reverse splits,
meetings, public exposes and tender offers (`--kind ipo` adds its IPO),
newest first. `idx stocks calendar [--from] [--to] [--kind ...]`: the
market's actions dated in the range (default today and 30 days ahead),
oldest first. MCP: get_corporate_actions, get_corporate_calendar.

Stockbit's `/corpaction/{type}` serves one kind per request; each type has
its own field prefix and list key, so entitlements are read by field
suffix. An action's `date` is the cum date for entitlements, else the
event's first day. Dividends keep their decimals. One request per kind,
cached 6 hours. AUTHERROR without a session.

Fixtures are the 2026-11-03 recordings (market-wide ones trimmed to
October-December). Goldens added; help-stocks and completions-bash gain
the two subcommands, MCP tools.json the two tools (regenerated with
UPDATE_GOLDEN=1). The MCP docs counted 17 tools without stockbit_login;
now 20.

Claude-Session: https://claude.ai/code/session_01RqPPVeVDrnLoP7NUZmLRxY

crates/idx-mcp/tests/golden/tools.json

@@ -235,6 +235,91 @@
     },
     "name": "get_company"
   },
+  {
+    "description": "Corporate actions of one IDX stock from the user's own Stockbit session, newest first: `kind` (dividend, stock-dividend, bonus, rights, warrant, split, reverse-split, meeting, expose, ipo, tender), `date` (the cum date for dividends, bonuses, rights and splits, i.e. the last day to buy and be entitled; else the event's first day), `ex_date`, `record_date`, `pay_date`, and per kind `cash_per_share` (IDR, may have decimals), `ratio` {old, new} (1:5 split = 1 share becomes 5; 655:104 rights = 104 rights per 655 held), `factor` (price adjustment), `price` (rights, warrant exercise, tender or IPO price, IDR), `period` and `exercise` {start, end}, `shares`, `percentage_bps`, `time`, `venue`. Absent fields are omitted. One Stockbit request per kind (about 1 s each on a cold cache, then cached 6 hours). AUTHERROR means there is no session: call stockbit_status, then stockbit_login.",
+    "inputSchema": {
+      "$schema": "https://json-schema.org/draft/2020-12/schema",
+      "properties": {
+        "kinds": {
+          "default": null,
+          "description": "Kinds to list (default: every kind but \"ipo\"). Each kind is one request to Stockbit.",
+          "items": {
+            "enum": [
+              "dividend",
+              "stock-dividend",
+              "bonus",
+              "rights",
+              "warrant",
+              "split",
+              "reverse-split",
+              "meeting",
+              "expose",
+              "ipo",
+              "tender"
+            ],
+            "type": "string"
+          },
+          "type": "array"
+        },
+        "symbol": {
+          "description": "IDX ticker, e.g. \"BBCA\".",
+          "type": "string"
+        }
+      },
+      "required": [
+        "symbol"
+      ],
+      "type": "object"
+    },
+    "name": "get_corporate_actions"
+  },
+  {
+    "description": "Corporate actions across IDX from the user's own Stockbit session, oldest first, dated from `from` to `to` (default today and the next 30 days): upcoming cum dates, meetings, exposes, rights, warrants, IPOs and tender offers, and the past year. Each item has the same fields as get_corporate_actions, with `symbol`. One Stockbit request per kind (about 1 s each on a cold cache, then cached 6 hours); pass `kinds` to ask for less. AUTHERROR means there is no session: call stockbit_status, then stockbit_login.",
+    "inputSchema": {
+      "$schema": "https://json-schema.org/draft/2020-12/schema",
+      "properties": {
+        "from": {
+          "default": null,
+          "description": "First day, YYYY-MM-DD (default today).",
+          "type": [
+            "string",
+            "null"
+          ]
+        },
+        "kinds": {
+          "default": null,
+          "description": "Kinds to list (default: every kind). Each kind is one request to Stockbit.",
+          "items": {
+            "enum": [
+              "dividend",
+              "stock-dividend",
+              "bonus",
+              "rights",
+              "warrant",
+              "split",
+              "reverse-split",
+              "meeting",
+              "expose",
+              "ipo",
+              "tender"
+            ],
+            "type": "string"
+          },
+          "type": "array"
+        },
+        "to": {
+          "default": null,
+          "description": "Last day, YYYY-MM-DD (default 30 days after `from`; at most 366 days).",
+          "type": [
+            "string",
+            "null"
+          ]
+        }
+      },
+      "type": "object"
+    },
+    "name": "get_corporate_calendar"
+  },
   {
     "description": "Foreign investors' buying and selling of one IDX ticker, session by session (oldest first), with range totals; end of day. With `source` \"ipot\" (default): `foreign_buy_value`, `foreign_sell_value` and `foreign_net_value` in IDR across all boards, `value` traded, and `foreign_share_bps` (foreign share of trading); share counts, close and `non_regular_bps` are null, and `rounded` = true means one decimal of precision. With \"idx\": exact foreign share counts on the regular board, values estimated at the session's average price, the close, `change_bps` and `non_regular_bps`.",
     "inputSchema": {