Add changelogs

Author: jasagredo

ouroboros-consensus-cardano/changelog.d/20251010_111741_javier.sagredo_version_tables.md

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+<!--
+A new scriv changelog fragment.
+
+Uncomment the section that is right (remove the HTML comment wrapper).
+For top level release notes, leave all the headers commented out.
+-->
+
+<!--
+### Patch
+
+- A bullet item for the Patch category.
+
+-->
+<!--
+### Non-Breaking
+
+- A bullet item for the Non-Breaking category.
+
+-->
+
+### Breaking
+
+- Flip serialization of `TxIx` in Mempack, to ensure lexicographic order on the
+  serialized form matches the Haskell Ord, allowing for incremental streaming of
+  values among backends. Note this happens at the same time as the versioning of
+  the LedgerTables codec which will induce a replay of the chain.

ouroboros-consensus/changelog.d/20251010_111745_javier.sagredo_version_tables.md

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+<!--
+A new scriv changelog fragment.
+
+Uncomment the section that is right (remove the HTML comment wrapper).
+For top level release notes, leave all the headers commented out.
+-->
+
+<!--
+### Patch
+
+- A bullet item for the Patch category.
+
+-->
+<!--
+### Non-Breaking
+
+- A bullet item for the Non-Breaking category.
+
+-->
+
+### Breaking
+
+- Version ledger tables encoding. Define `TablesCodecVersion1`.
+- InMemory snapshots used to store the tables in `<snap>/tables/tvar`. Now they
+  store the tables in `<snap>/tables`.