Make fims::Vector out-of-bounds errors actionable with vector identity, index, and size

[Copilot]

fims::Vector bounds failures currently return a generic message, which makes it hard to identify the offending vector in model wiring. This updates vector metadata and error formatting so out-of-bounds exceptions point directly to the source and failing index.

• fims::Vector error payload improvements

  • Added variable_name_m to fims::Vector with set_variable_name() / get_variable_name().
  • Updated both operator[] overloads (const and non-const) to throw:
    • vector name (when available),
    • 1-based index (R-facing),
    • vector size.
  • Kept behavior unchanged aside from richer exception text.

• Rcpp object wiring now names vectors at construction

  • Set set_variable_name(...) on vectors created/populated in:
    • selectivity, recruitment, maturity, population, fleet, distribution interfaces,
    • model-derived quantity vectors in rcpp_models.hpp.
  • Naming follows existing parameter-path conventions (e.g., Recruitment.<id>.log_devs, Fleet.<id>.log_Fmort), so errors align with registered parameter names.

• Focused coverage for new diagnostics

  • Added a gtest for fims::Vector::operator[] bounds exceptions (const + non-const).
  • Asserts message contains: base error text, vector name, 1-based index, and size.

fims::Vector<double> values(2, 0.0);
values.set_variable_name("Recruitment.1.log_devs");
(void)values[2];
// throws: "fims::Vector out of bounds for Recruitment.1.log_devs: index 3 >= size 2"

• Fixes make fims::Vector out of bounds error more informative #1412