feat(cli): reward prose-first, consolidated hubs over claim-logs (#142)

[Connorrmcd6]

Summary

Agents using surf write claim-logs — one claim per function, near-1:1 symbol→claim, almost no prose — because the CLI's in-loop signals reward it. Those signals (read every iteration) teach far more than prose docs (read once). This PR adds the missing counter-pressure that rewards prose and consolidation, then refactors our own flagged hubs to match.

Closes #142.

What changed & why

1. surf suggest reframed (surf-cli/src/suggest.rs) — highest leverage. Human output no longer reads as "a list of claims to write." It states these are undocumented symbols, groups them by file, and emits a single multi-site at: skeleton with prose-first scaffolding, so the default shape models a good hub. --format json is byte-unchanged (the json_shape_has_no_hash contract holds).

2. Symmetric claim-level lint nudges (surf-cli/src/lint.rs) — both advisory, exit-0, never blocking, mirroring the existing lint_coarse_span pattern:

• claim-log — a hub with ≥4 claims that never once uses a multi-site at: list (the per-symbol smell). A hub that consolidates even one behavior is exempt.
• thin-prose — a multi-claim hub whose body prose (code fences excluded) is below ~15 words/claim.

3. Prose-first surf new scaffold (surf-cli/src/new.rs) — ships ## How it works / ## Boundary headings and a multi-anchor example claim (stays anchors: [], so lint-clean).

4. Docs — docs/guides/authoring-hubs.md promotes the multi-site at: list from a staleness footnote to the default for system claims and adds an "A hub is an onboarding doc" section with a good/bad contrast; AGENTS.md step 4 now says extend an existing claim's prose / add an anchor site before writing a new granular claim.

5. Dogfooding the change. The new warnings flagged 6 of our own hubs. Fixed all 6:

• Added real onboarding prose to the 5 thin hubs (cli-check, cli-workspace, hash, hub-format, cli-git) — body-only, no hashes touched.
• Gave cli-git the repo's first multi-site claim: one invariant (every git query degrades to None; the verdict never depends on it) sealed across all five helpers, letting us trim per-function boilerplate. Re-stamped via surf verify.
• Logged the moment (and its resolution) in docs/dogfood-log.md.

New-warning hits on our hubs: 6 → 0. (The 16 pre-existing under-coverage warnings predate this PR and are left as separate cleanup.)

Verification

All run on this branch:

Gate	Result
cargo fmt --all --check	✅ clean
cargo clippy --all-targets --all-features -- -D warnings	✅ no warnings
cargo test --all	✅ 202 passed, 0 failed (2 ignored)
surf check (dogfood)	✅ all anchored spans match
surf lint (dogfood)	✅ exit 0; 0 claim-log, 0 thin-prose; 16 pre-existing under-coverage

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