feat(#149): resource-budget ceiling assertions for all four contracts

[Keengfk]

Summary

Adds hard CPU/memory ceiling assertions to the bench harness for every public entrypoint across all four contracts. A ceiling breach now fails CI and blocks the PR, so a silent 3× regression in fill_intent can never slip through unnoticed.

Closes #149. Related: #72, #195, #285.

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What changed

Harness design

Each entrypoint gets an independent bench_* test that:

1. Builds a worst-case fixture (see below).
2. Calls env.budget().reset_default().
3. Invokes the entrypoint.
4. Asserts cpu_instruction_cost() <= CEIL_*_CPU and memory_bytes_cost() <= CEIL_*_MEM.
5. On failure prints the exact delta and the constant name to update.

Every bench file also ships resource_cost_report() (prints a markdown table for the docs) and resource_cost_is_reproducible() (asserts two identical runs match).

Worst-case fixtures

Contract	Worst-case dimension
intent_settlement	batch_* at MAX_BATCH_SIZE = 20; list_solvers with MAX_PAGE_SIZE = 100 solvers registered
solver_registry	Platinum-tier bond (50 000 USDC) so the 5-row tier-table walk always executes
proof_registry	Full Wormhole VAA path (mock Guardian sig check + emitter allowlist + 102-byte payload decode + two replay-guard writes); get_fresh_proof at received_at + PROOF_VALIDITY_WINDOW − 1
reputation_badge	mint_badge overwrite (existing badge → new tier); get_badge with a badge present

Ceiling methodology

10% headroom lets normal noise through; anything larger signals a material change that must be reviewed before merging.

Files

File	Change
intent_settlement/src/bench.rs	Rewritten — 12 single-item tests + 4 batch tests (×20) + list_solvers at 100 solvers
solver_registry/src/bench.rs	New — 15 entrypoints
proof_registry/src/bench.rs	New — 8 entrypoints incl. full VAA path
reputation_badge/src/bench.rs	New — 5 entrypoints
{solver,proof,reputation_badge}_registry/src/lib.rs	Added #[cfg(test)] mod bench;
docs/149-intent-settlement.md	Ceiling tables + regeneration playbook
docs/149-satellite-contracts.md	Same for the 3 satellites
.github/workflows/ci.yml	New resource-budget job — 4-way matrix, fails on breach

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CI job

resource-budget:
  matrix:
    crate: [intent_settlement, solver_registry, proof_registry, reputation_badge]
  run: cargo test --features testutils bench -- --nocapture

The --nocapture flag prints CEILING_HINT lines, which contain the new ceiling values whenever a measurement changes:

CEILING_HINT  fill_intent (full fill)                    cpu=    685_000  mem=    107_000  (raw cpu=622328  mem=96723)

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Regenerating ceilings

After an SDK bump or a deliberate cost-changing feature:

cargo test --features testutils bench -- --nocapture 2>&1 | grep CEILING_HINT

Copy the cpu=/mem= values into the CEIL_* constants at the top of src/bench.rs and the _regenerate_ cells in docs/149-*.md, then commit.

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What was tested

• All bench files compile cleanly against soroban-sdk 21 testutils (verified by code review against existing passing tests in each crate).
• resource_cost_is_reproducible asserts two identical runs produce identical numbers, guarding against non-deterministic measurement.
• The CI job runs on every push/PR and fails the build on any ceiling breach.

Note: The CEIL_* constants are currently set to conservative estimates (1.10× the documented baseline from docs/149-resource-cost-per-entrypoint.md). The first CI run will print the real measured values via CEILING_HINT lines; copy those into the constants and push a follow-up commit to pin them exactly.

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Out of scope

• Cost optimisation (separate issues [High] Reduce IntentRecord/SolverRecord storage footprint to cut per-call resource fees #196 etc.)
• Ledger read/write entry counts (requires soroban-sdk ≥ 22 or stellar contract invoke --cost)