Download Syncthing 2.0.4

Major changes in 2.0
- Database backend switched from LevelDB to SQLite. There is a migration on first launch which can be lengthy for larger setups. The new database is easier to understand and maintain and, hopefully, less buggy.
- The logging format has changed to use structured log entries (a message plus several key-value pairs). Additionally, we can now control the log level per package, and a new log level WARNING has been inserted between INFO and ERROR (which was previously known as WARNING...). The INFO level has become more verbose, indicating the sync actions taken by Syncthing. A new command line flag `--log-level` sets the default log level for all packages, and the `STTRACE` environment variable and GUI has been updated to set log levels per package. The `--verbose` and `--logflags` command line options have been removed and will be ignored if given.
- Deleted items are no longer kept forever in the database, instead they are forgotten after fifteen months. If your use case require deletes to take effect after more than a fifteen month delay, set the `--db-delete-retention-interval` command line option or corresponding environment variable to zero, or a longer time interval of your choosing.
- Modernised command line options parsing. Old single-dash long options are no longer supported, e.g. `-home` must be given as `--home`. Some options have been renamed, others have become subcommands. All serve options are now also accepted as environment variables. See `syncthing --help` and `syncthing serve --help` for details.
- Rolling hash detection of shifted data is no longer supported as this effectively never helped. Instead, scanning and syncing is faster and more efficient without it.
- A "default folder" is no longer created on first startup.
- Multiple connections are now used by default between v2 devices. The new default value is to use three connections: one for index metadata and two for data exchange.
- The following platforms unfortunately no longer get prebuilt binaries for download at syncthing.net and on GitHub, due to complexities related to cross compilation with SQLite:
- dragonfly/amd64
- illumos/amd64 and solaris/amd64
- linux/ppc64
- netbsd/*
- openbsd/386 and openbsd/arm
- windows/arm
- The handling of conflict resolution involving deleted files has changed. A delete can now be the winning outcome of conflict resolution, resulting in the deleted file being moved to a conflict copy.

This release is also available as:
- APT repository: https://apt.syncthing.net/
- Docker image: `docker.io/syncthing/syncthing:2.0.4` or `ghcr.io/syncthing/syncthing:2.0.4` (`{docker,ghcr}.io/syncthing/syncthing:2` to follow just the major version)

What's Changed
Fixes
- fix(cmd): only start temporary API server during migration if it's enabled by @pixelspark in #10284
- fix(model): consider MaxFolderConcurrency when calculating number of hashers by @tomasz1986 in #10285
- fix(model): consider number of CPU cores when calculating hashers on interactive OS (#10284) by @tomasz1986 in #10286
- fix(db): apply all migrations and schema in one transaction by @calmh in #10323
- fix(model): correctly handle block-aligned empty sparse files by @calmh in #10332
- fix(syncthing): apply folder migrations with temporary API/GUI server by @calmh in #10330
Other
- chore(db): adjust db bench name to improve benchstat grouping by @imsodin in #10283
- chore(db): cleanup DB in tests and remove OpenTemp by @imsodin in #10282
- build: use Go 1.24 tools pattern by @calmh in #10281
- chore(db): avoid rowid for blocks and blocklists by @bt90 in #10315
- refactor(db): slightly improve insert performance by @calmh in #10318
- chore(gui): use steps of 1024 KiB for bandwidth rate limits by @tomasz1986 in #10316
- chore(gui): use step of 3600 for versions cleanup interval by @tomasz1986 in #10317
- chore(db): benchmark output, migration blocks/s output by @calmh in #10320
- chore(db): update schema version in the same transaction as migration by @imsodin in #10321
- chore(db): migration for previous commits by @calmh in #10319

Full Changelog: https://github.com/syncthing/syncthing/compare/v2.0.3...v2.0.4