0.5.0-rc.3

• chore: remove utils/scripts/relocate-lines.rs
• release: breaking version bumps for the gettxoutsetinfo gate
• refactor(zaino-state): factor migration Stage C into a module method
• refactor(zaino-state): factor write_block accumulator glue into module methods
• refactor(zaino-state): move the accumulator assertion helper into the module
• refactor(zaino-state): move the accumulator test oracle into the module
• refactor(zaino-state): fold the DbV1 accumulator db accessor into the module
• refactor(zaino-state): co-locate FinalisedSource accumulator dispatch in the module
• refactor(zaino-state): coalesce gettxoutsetinfo cfg attributes
• refactor(zaino-state): DRY the accumulator write path into fns
• tools: add relocate-lines.rs for bulk line-range file moves
• refactor(zaino-state): move accumulator tests into the gated module
• ci: build both gettxoutsetinfo feature states
• refactor(zaino-state): extract the txout-set accumulator into its own module
• feat(zaino-state): gate gettxoutsetinfo + txout-set accumulator behind a non-default feature
• refactor(zaino-state): extract DbV1::open_env_and_dbs shared opener
• Remove legacy v0 finalised-state schema
• refactor(zaino-state): DRY the DbV1 detached-handle idiom