fix(producer): attribute and stop oversized plans early

[jrusso1020]

What

• add an exact, symlink-safe plan-size breakdown with fixed or hashed component labels
• reject oversized plans after the compiled tree stabilizes, before video extraction
• reject again after artifact promotion but before the full freeze/hash read
• retain the exact post-freeze ceiling check and existing PLAN_TOO_LARGE contract/message prefix
• remove only freeze-owned stale metadata before the preliminary check when callers reuse a plan directory

Why

The existing ceiling only runs after a multi-GiB plan has been fully materialized and hashed. Production examples range from roughly 3 GiB to 12.6 GiB. This gives us enough attribution to design Plan v2 from real data while avoiding obviously wasted extraction and hashing work.

Compatibility and rollout

• no v1 plan artifact or plan.json format changes
• no queue, routing, retry, worker-count, or steady-state render changes
• under-limit plan bytes/hashes remain governed by the existing freeze path
• intended for the candidate sidecar and canary lane before broader rollout

This does not interrupt a single FFmpeg extraction once it is running. A canaried extraction-budget monitor is a separate follow-up.

Validation

• focused distributed-plan tests: 54 passed
• full producer unit lane: 31 Vitest files / 384 tests plus all classified Bun lanes passed
• typecheck, lint, format, Fallow, tracked-artifact checks passed
• independent code review approved