v0.24.0 — Budget-cap security fixes

A whole-codebase audit (8 review angles, every finding adversarially re-verified) found that the v0.23.0 budget cap — the wallet-drain guardrail — had four independent bypasses. This release closes all of them plus a batch of correctness and robustness fixes.

Security / budget integrity

• Path traversal in passthrough tools — rpc/surf/modal/phone/exa/search/defi/markets only stripped slashes, so a .. segment (incl. %2e%2e / .%2e / backslash encodings the URL parser normalizes) escaped the namespace and re-routed cheap calls onto expensive paid endpoints, defeating the per-tool budget pre-check and profile scoping. New path-safety guards reject traversal/invalid chain slugs before any spend.
• Concurrent-spend TOCTOU — checkBudget only read spent; concurrent calls each passed a stale total and overran the cap. New reserveBudget() atomically checks and reserves the estimate, released in finally across all 15 paid tools.
• routing:"smart" + routing_profile:"free" reserved $0 but routed to a paid model — unmetered drain. Removed the $0 special-case; corrected the misleading schema copy.

Correctness / robustness

• Manual-402 media tools no longer report a 5xx/429/425 outage as "fund your wallet"; formatError no longer reads $402.50 as a status code; music/video guard the probe-body parse.
• --profile constructor/__proto__ falls back to full instead of crashing; a lagging RPC no longer yields $NaN USDC; fetchWithTimeout covers a stalled body; remote reference images are rejected by Content-Length before buffering; the key-leak scanner catches bare 64-hex keys.
• JSON mode now honored on the native anthropic/claude-* path; routing:"smart" + multi-turn messages returns a clear error instead of dropping history.
• Dead ServerContext removed; realface enroll deduped onto payAndPostJson.

64 unit tests (29 new). Full details in CHANGELOG.md.