fix(pkg): bound local mirror package archives before allocation

[TheHalfMoon]

Finding

Canonical LocalMirrorSource::archive reads <root>/<package>/<version>/package.tgz with unbounded fs::read, while the public registry transport enforces a 128 MiB compressed archive body limit before further archive traversal bounds apply.

Canonical base inspected:

main: 8a45857bf31c4acae57fdfb1e3cdde3d0f7d0361

This means a caller-selected local mirror file can force allocation of an arbitrarily large file before commandF applies manifest/decompressed/entry limits.

Risk

Local untrusted-input resource exhaustion / assurance asymmetry. No remote exploitability is claimed. Local/offline operation should not silently have a weaker archive-size boundary than network acquisition unless the difference is explicit and justified.

Required repair

• define/reuse a commandF-owned compressed package archive size bound for local mirror acquisition;
• inspect metadata/stream at most bound+1 before allocating/returning the archive bytes;
• align with the registry's 128 MiB limit unless legitimate public/local package evidence requires a documented different bound;
• preserve package-not-found behavior, provenance/source identity, manifest traversal bounds, and resolver semantics;
• audit other local file acquisition paths for the same allocate-before-bound pattern.

Tests

• exact compressed bound accepted when otherwise valid;
• bound+1 rejected before complete allocation/manifest parsing;
• ordinary local-mirror resolution remains deterministic;
• malformed/oversized local archive fails closed with stable error classification;
• no regression in real registry path or archive manifest bounds.

Governance

• keep separate from AF-01 planning PR docs(assurance): plan trusted development baseline #34;
• no CF-06 production pin or CF-10 corpus change;
• no resolver semantic widening;
• exact-head mandatory CI + path-applicable proofs + CodeRabbit/Qodo before merge.