Make library sourcing passive and initialization explicit

[codeforester]

Parent: #214

Train position: 8 of 26
Phase: P1 — Passive, stable runtime and API

Problem

Sourcing lib_std.sh currently filters caller arguments, resets positional parameters, exports logging controls, and creates or unsets generic state. That makes a reusable library behave like an application bootstrap and creates surprising integration failures.

Acceptance criteria

• Make sourcing define public symbols, immutable package metadata, and collision-safe load guards without consuming or rewriting $@.
• Do not install traps, export runtime controls, change shell state, or create, unset, or overwrite caller-owned generic variables at source time.
• Introduce an explicit, idempotent initialization API that accepts argv and configuration as inputs and returns filtered application arguments without hidden positional mutation.
• Move wrapper flags, logging and color initialization, and application lifecycle setup into the launcher or explicit initialization.
• Make repeated sourcing, repeated initialization, and loading compatible or incompatible versions deterministic and diagnosable.
• Provide a tested one-time v1.4.0-to-v2 migration path and prove the legacy source-time mutations are absent; do not retain them behind a compatibility mode.

Dependencies

• Guarantee public APIs under caller-selected Bash options #216

Completion

Implemented by PR #250 (merged 2026-08-04). Local validation passed all 475 BATS tests, Bash 4.2 compatibility smoke checks, all eight Bash option-contract modes, examples, and ShellCheck error-profile validation. Hosted Ubuntu and macOS checks also passed.