Rust perf: cache LazyLock pricing table; hoist regex statics

[willwashburn]

Context

Several allocate-per-call hotspots that turn into LazyLock<T> one-liners.

1. crates/relayburn-sdk/src/analyze/pricing.rs:94-96 load_builtin_pricing() re-parses the embedded models.dev JSON snapshot every call. It's invoked from at least 5 public verbs in query_verbs.rs. Wrap in static BUILTIN: LazyLock<PricingTable> and .clone() once (or return Arc<PricingTable>).

2. Per-call regex compilation:

• crates/relayburn-sdk/src/analyze/ghost_surface.rs:298-302 claude_command_name_re()
• crates/relayburn-sdk/src/analyze/claude_md.rs:249-250 open_re, heading_re inside find_headings (called per overhead file)
• crates/relayburn-sdk/src/reader/classifier.rs:680-682 and :725-726 declare the same static RE: LazyLock<Regex> for ^[A-Za-z_][A-Za-z0-9_]*= — two cells for one pattern; lift to module scope.

provider_reattribution.rs:DEFAULT_RULES_INNER already uses LazyLock; this is the same trick applied consistently.

3. crates/relayburn-sdk/src/analyze/cost.rs:126-149 sum_costs allocates model: "aggregate".to_string() for every call regardless of input length. Make model: &'static str (or Cow<'static, str> if a callsite needs ownership).

Proposed fix

Mechanical: wrap each in LazyLock::new(...) (already an MSRV-stable feature with the toolchain pinned at 1.94). Verify the conformance gate stays green.

References

• crates/relayburn-sdk/src/analyze/pricing.rs:94-96
• crates/relayburn-sdk/src/analyze/ghost_surface.rs:298-302
• crates/relayburn-sdk/src/analyze/claude_md.rs:249-250
• crates/relayburn-sdk/src/reader/classifier.rs:680-682, 725-726
• crates/relayburn-sdk/src/analyze/cost.rs:126-149
• Analyze + reader review notes from the May 2026 Rust review.