feat: add map step infrastructure, support for .map() DSL method, and improve failure handling

- Renamed existing changesets for clarity
- Implemented map step type infrastructure in SQL core
- Added .map() method to Flow DSL with compile-time validation and type safety
- Enhanced failure handling to archive all pending messages on run failure
- Fixed type contract violations to fail immediately without retries
- Updated documentation and created detailed changeset
- Removed obsolete plan files and consolidated migration strategy
- Improved robustness and observability for map steps and failure scenarios

Author: jumski

.changeset/tricky-sites-stare.md renamed to .changeset/add-array-method-to-dsl.md

@@ -1,5 +1,5 @@
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-'@pgflow/dsl': patch
+'@pgflow/dsl': minor
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 Add `.map()` method to Flow DSL for defining map-type steps

.changeset/easy-bats-nail.md renamed to .changeset/add-map-method-to-dsl.md

@@ -1,5 +1,5 @@
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-'@pgflow/core': patch
+'@pgflow/core': minor
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 Add map step type infrastructure in SQL core

.changeset/yummy-geckos-marry.md renamed to .changeset/add-map-step-type-infrastructure.md

@@ -1,5 +1,5 @@
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-'@pgflow/cli': patch
+'pgflow': patch
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 Fix: Use --config instead of --import-map for Deno compilation