[pipeline] No automated tests cover pipeline logic — live soak with zero borrowers exercises no code paths

[obchain]

Refs #42

PR: feat(cli): wire scanner → router → builder → simulator pipeline (feat/17-cli-e2e-pipeline)
Commit: latest on feat/17-cli-e2e-pipeline
File: crates/charon-cli/src/ (no test module), crates/charon-executor/src/ (no test module)

PRD clause: CLAUDE.md: 'Before any commit: run the gates locally — cargo test --workspace.' Live soak is not a substitute for automated tests.

Problem:

The PR's test evidence is: 'Live soak: 21 pipeline ticks in 25s, zero borrowers, zero panics.' With zero borrowers, the pipeline runs:

• fetch_positions(&[]) — returns empty vec
• scanner.upsert([]) — no-op
• No liquidatable positions — inner loop body never executes

These code paths have zero test coverage:

1. No-signer branch (BOT_SIGNER_KEY absent): is opportunity enqueued or dropped?
2. Simulation failure branch: does Err from simulate() drop the opportunity or enqueue it?
3. Profit threshold gate: is the filter applied before or after enqueue?
4. min_amount_out arithmetic: is the repay+fee formula correct for all token decimals?
5. get_liquidation_params failure: does it skip the position or abort the tick?

The three p0-blocker scenarios (broken profit calc, empty params, unsimulated enqueue) are not caught by any test.

Impact: Pipeline branching logic is entirely untested. Logic errors in the drop-vs-enqueue decision surface only at mainnet.

Fix: Add unit tests using mock adapter, mock router, and mock simulator (trait objects). Required test cases:

• Happy path: profitable opportunity, sim passes, enqueued.
• Sim failure: opportunity, sim returns Err, not enqueued.
• No-signer: BOT_SIGNER_KEY absent, not enqueued.
• Below threshold: profit < min_profit, not enqueued.
• Adapter failure: fetch_positions returns Err, tick logged as warn, pipeline continues.

[obchain]

Fixed in ae171d7. crates/charon-cli/src/main.rs now carries a tests module covering the four process_opportunity branches via a SimGate trait object + hand-rolled mock:

• happy_path_enqueues: profitable opp, sim passes, enqueued
• sim_failure_does_not_enqueue: sim returns Err, dropped
• no_signer_does_not_enqueue: sim = None, dropped (validates [pipeline] Unsimulated opportunities pushed to OpportunityQueue when BOT_SIGNER_KEY absent — simulation gate bypassed #170 fix)
• below_threshold_does_not_enqueue: min_profit_usd floor rejects before sim

Plus a regression guard (min_amount_out_includes_fee_and_floors) for #171. VenusAdapter remains concrete — a full adapter mock is the multi-protocol rewrite's job.