Adds scripts/Check-Deps.ps1 and wires it into Deploy-Brass.ps1 as a
pre-flight gate when Stage includes Pack. The script parses each lockfile
jar's META-INF/neoforge.mods.toml directly -- the same source the loader
reads at startup -- and refuses to deploy if any [[dependencies]] block
with type=required (default) names a modId that nobody in the pack
provides.
Handles three real edge cases discovered during initial run:
1. Jar-in-jar bundled deps: Create ships Ponder, Registrate, Flywheel
embedded under META-INF/jarjar/. The script recurses into those and
counts their modIds as present, since the loader auto-loads them.
2. Language-provider jars (Kotlin for Forge) have no standard mods.toml
-- they declare via a different mechanism. Tiny slugToImplicitModId
override map (currently 1 entry) covers them.
3. Non-mod lockfile entries (shaderpacks under shaderpacks/, configs
under config/, etc.) are skipped explicitly by path prefix check.
Vanilla deps (minecraft, neoforge, forge, fabric, java, javafml, etc.)
are pre-seeded as present.
Jars cached at /tmp/bns-check-deps-cache/<sha1>.jar; second-run cost is
~1.5s. First run downloads ~150MB.
The script would have caught the v0.15.0 -> v0.15.1 incident: Slice &
Dice's jar declares kotlinforforge required in mods.toml even though
Modrinth's dep field only lists Create. The Modrinth-only check (earlier
draft) wouldn't have helped; the mods.toml-based check does.
