Native module catalog: Starship / Oh My Posh coverage audit and prioritized ports #364

Goal

Turn the broad #305 Native module ecosystem into a finite, evidence-backed catalog-coverage pass. Do not chase a fictional 600-module parity target or duplicate external providers.

Current baseline

On release/v0.18.0, src/context/modules.ts declares 10 built-in module IDs and seven src/context/packs/builtin/*.json packs contribute 25 module definitions (35 native/pack entries total at that ref). This is not a measurement of every fact, provider feature or optional external configuration. Recount after upstream changes.
Starship and Oh My Posh have wider catalogs; count and map meaningful functions, not aliases or formatting-only entries. Both are already supported as external prompt providers in NMSh.

Scope

• Build a matrix: upstream module/segment → NMSh native/core capability, bundled pack, generic-toolchain coverage, external provider only, missing, intentionally excluded. Cite upstream official docs and exact NMSh implementation. Note provider/config differences and false equivalences.
• Prioritize real gaps: additional language/runtime families (Ruby, PHP, Swift, Kotlin, Dart/Flutter, Lua, Zig, .NET, Elixir, etc.); build/package tools (Gradle/Maven/CMake/Bazel); Conda/Pixi/Nix and additional environments; useful VCS cases including Jujutsu. Choose based on use cases and safe local evidence.
• Native capabilities must remain demand-driven, bounded, cached, private and non-executable by default. Adding a first-party capability requires source/permission review, hostile-workspace fixtures, and clear provenance. Never run repo-provided binaries or scripts merely to populate a prompt.
• Keep native module UX focused: /modules and existing surfaces, conditional visibility, compact fallback, accurate unavailable/unknown states.
• Evaluate upstream format/theme import as a separate feature under #304, not an automatic conversion of arbitrary templating or shell hooks.

Acceptance

• Publish dated, sourced coverage matrix and identify what NMSh actually supports today.
• Rank high-value, distinct additions in small coherent slices; defer lower-value duplications explicitly.
• Add/extend capabilities with dedicated tests and documentation only after review of sources and safety; no arbitrary code execution.
• Track implementation slices under NMSh Native module ecosystem and upstream module ports #305 rather than opening an issue for each language.
• Preserve external Starship and Oh My Posh provider functionality and performance.

Related: #305, #304, #321 (security/performance/host QA).