Cleanup: verify LFS 512 KiB policy in code + docs

[pewpewpotato]

Problem

LFS policy is locked (default 512 KiB; text/JSON/TOML plain with warn ~1 MiB). Confirm code + docs match; finish or strip any stubbed #103 leftovers.

Who it’s for

Agents writing assets; humans cloning context repos.

Acceptance criteria

• Code enforces 512 KiB default (configurable) consistent with Strategy: spec solution-shared context git remote #99/Strategy: context assets via Git LFS above threshold #103 locks
• Docs match code (no stubbed “coming soon” LFS that isn’t real)
• If anything is half-implemented: finish or remove the mention
• Close or supersede any stale Strategy: context assets via Git LFS above threshold #103 work if already done elsewhere

Priority

Fourth of the post-pivot cleanup slice.

Related

May overlap #103 — verify status first.

Owner

Spool Technical Lead