chore: bump version to v0.5.5

[flyworker]

Prepares the v0.5.5 tag. main is seven commits past v0.5.4 while BuildVersion still reads 0.5.4, so builds cut from main report a version whose release does not contain them.

Since v0.5.4:

• feat(dashboard): lift earnings above GPU capacity, inline the health summary #124 — earnings lifted above GPU capacity, health summary inlined
• fix(dashboard): bucket earnings by day past 24h, and label points by their span #125 — earnings bucketed by day past 24h, points labelled by their span
• feat: persist request history so Transactions survives a restart #126 — request history persisted, so Transactions survives a restart
• feat(dashboard): price earnings history from the platform's own figure #127 — earnings history priced from the platform's own figure
• feat(inference): declare how a context window was determined #129 — context windows declare how they were determined
• fix: stop the registry callbacks erasing context_length and local_model #130 — fix: models.json context_length was being erased by the registry callbacks
• fix: validate model output during warmup #132 — warmup validates model output instead of discarding it

go build ./... and go test ./... pass.