fix(import): detect and import the Setapp edition of TablePlus

[datlechin]

Closes #1528.

Problem

Importing from TablePlus reported "TablePlus is not installed" when the installed copy was the Setapp edition. TablePlusImporter hardcoded the standalone edition in three places:

• appBundleIdentifier = "com.tinyapp.TablePlus", so the LaunchServices lookup behind installedAppURL()/isAvailable() never matched the Setapp bundle id com.tinyapp.TablePlus-setapp.
• connectionsFileURL and groupsFileURL were pinned to .../com.tinyapp.TablePlus/Data/..., so even if detection passed, a Setapp user's connections (under com.tinyapp.TablePlus-setapp/Data/) would not be read.

Change

TablePlusImporter is now edition-aware, following the existing DBeaverImporter multi-edition pattern:

• A knownBundleIdentifiers list (standalone first, then Setapp). installedAppURL() returns the first installed edition, so detection and the source-picker icon work for Setapp.
• connectionsFileURL/groupsFileURL are computed from the installed edition's data folder instead of a hardcoded path. A pure dataDirectory(for:home:) builds the path.
• appBundleIdentifier stays the standalone id (canonical for registry metadata).
• The keychain service com.tableplus.TablePlus is shared across editions, so it is unchanged.

The Setapp edition is not sandboxed (its plugins live under the real ~/Library/Application Support/com.tinyapp.TablePlus-setapp/), so it mirrors the standalone Data/ layout and needs no container-path handling. The Mac App Store edition's bundle id is undocumented, so it is intentionally not added.

Tests

App detection and data-path resolution are now driven through injectable seams (resolveAppURL, dataDirectoryOverride), so the cases are deterministic without a real install. Added: Setapp detection, standalone-preferred-when-both-installed, no-edition-installed, the dataDirectory(for:home:) path, and connectionsFileURL following the Setapp edition (with standalone fallback).

This also fixes two pre-existing isAvailable tests that were leftovers from before detection moved to LaunchServices (#1305): they asserted file-based availability against an app-based check, so they passed or failed depending on whether TablePlus was installed on the test runner.