chore: bump version to v0.3.0

Release highlights:
- feat: fetch query results as Arrow IPC (replaces JSON row format)
- feat: async query polling loop replaces exit-code-2 behaviour
- feat: --database flag on hotdata query for managed databases
- feat: databases show subcommand
- feat: databases tables <db> positional shorthand for tables list
- feat: background update-available notice printed after command output
- feat: hotdata update auto-installs/updates agent skills
- feat: hotdata update executes brew upgrade for Homebrew installs
- fix: remove dead AsyncResponse.status field (compiler warning)
- fix: reorder polling loop (poll first, sleep last)
- fix: 120s timeout on skills HTTP download client
- fix: replace chained .unwrap() with .expect() in tables help path

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

Author: eddietejeda

Cargo.lock

@@ -1,6 +1,6 @@
 [package]
 name = "hotdata-cli"
-version = "0.2.9"
+version = "0.3.0"
 edition = "2024"
 repository = "https://github.com/hotdata-dev/hotdata-cli"
 description = "CLI tool for Hotdata.dev"