fix(companies): align optional numeric fields with API validation

Make employee_count, annual_revenue, and founded_year truly optional in
the create company form and payload. Add field validation docs and
Cypress e2e coverage for dashboard and notifications.

Co-authored-by: Cursor <cursoragent@cursor.com>

docs/client/create-company-field-validations.md

@@ -0,0 +1,32 @@
+# Create Company Field Validations
+
+This document describes validation rules for selected fields in the `Create Company` API request body (`POST /admin/v1/companies`).
+
+Source of truth: `internal/company/form.go` (`CompanyForm`).
+
+## employee_count
+
+- JSON field: `employee_count`
+- Type: `integer` (`*int`, optional)
+- Validation tag: `optional,range(1|100000)`
+- Rules:
+  - Field is optional.
+  - If provided, value must be between `1` and `100000` (inclusive).
+
+## annual_revenue
+
+- JSON field: `annual_revenue`
+- Type: `number` (`*float64`, optional)
+- Validation tag: `optional,range(0|999999999999)`
+- Rules:
+  - Field is optional.
+  - If provided, value must be between `0` and `999999999999` (inclusive).
+
+## founded_year
+
+- JSON field: `founded_year`
+- Type: `integer` (`*int`, optional)
+- Validation tag: `optional,range(1800|2100)`
+- Rules:
+  - Field is optional.
+  - If provided, value must be between `1800` and `2100` (inclusive).