chore: release hotdata v0.19.0

[shefeek-jinnah]

Release hotdata v0.19.0: version bumped in Cargo.toml and CHANGELOG.md updated. After merge, run ./scripts/release.sh publish from a clean main checkout.

[claude]

nit: update the three README version pins to "0.19" (not blocking).

README.md pins hotdata = "0.18" at lines 17, 32 and 210. Cargo treats "0.18" on a 0.x crate as >=0.18.0, <0.19.0, so a reader who copies the install snippet resolves 0.18.1 and never gets this release. The README ships with the crate to crates.io, so the stale pin is the first thing a new user sees.

scripts/release.sh only stages Cargo.toml and CHANGELOG.md, so no tooling catches this drift on a minor bump.

[shefeek-jinnah]

Fixed in 4f374bf: all three README pins are now 0.19.

[claude]

super nit: rewrite the two entries below as user-facing prose and move the feature under ### Added (not blocking).

Lines 15-16 are raw commit subjects. Every prior section in CHANGELOG.md describes the change and its effect on callers. chore(databases): simplify fork error description is internal and carries no meaning for a crate consumer. scripts/extract-changelog.py feeds this section into the GitHub Release body, so the text reaches users verbatim. A release PR is the last chance to edit the text before the tag.

[shefeek-jinnah]

Fixed in 4f374bf. I rewrote the section as user-facing prose under Added and Changed. The #149 regen turned out to carry more than its title said: the constant-per-key endpoints, vector index precision, and a breaking rename of key_determines to constant_per_key. All of these are now listed.

[claude]

Both prior nits are resolved. Verified the changelog claims against the tree: set_database_table_constant_per_key (src/apis/databases_api.rs:1252), set_managed_table_constant_per_key (src/apis/connections_api.rs:709), JobType::TableConstantsUpdate (src/models/job_type.rs:41), vector_precision on the three index models, and description on ForkDatabaseRequest, ForkedFromInfo, LineageAncestorInfo and LineageForkInfo. No 0.18 reference remains outside the changelog history.