Let's capture our plans relating to the v1 release, ideally including dependencies and the critical path, in this tracking issue.

• Revisit version number conversation: decide whether this should be v0.39.0 or v1.0.0 (see #357)
  • A decision was taken to cut this as v1
• proto: protobuf renaming and versioning #1330
• rpc: Version the RPC APIs #75
• ADR 109: Reduce Go API surface area #1484
• mempool: Reject incoming txs while catching up #785
• Reach a decision on support policy #590 to be able to specify upfront the support policy for v1
• consensus: proposer-based timestamps (PBTS) #1731
• cli: update the cometbft version command to output the v1 version #2543
• Tag api/v1.0.0-alpha.1 just prior to tagging v1.0.0-alpha.1
• @adizere last /internal packages checks before we cut the RC
  • docs(ADR-114): Partly Undo ADR 109 (Reduce Go API Surface) #2897
  • revert(internal): Implement ADR 114 by making several modules public again #3004
• Cosmos SDK: provide an API for accessing state and store #2610

For Release Candidate

• v1 QA #2100
• PBTS: Don't check synchrony parameters when PBTS is not enabled #2580

For RC1 release (v1.0.0-rc1)

• Tag api/v1.0.0-rc.1 just prior to tagging v1.0.0-rc.1 #3190
• update api in cometbft go.mod to v1.0.0-rc.1 #3191
• chore: file updates for the v1.0.0-rc1 release #3189

For RC2 release (v1.0.0.-rc2)

• chore: updates in preparation for v1.0.0-rc2 #4454
• chore(release): v1.0.0-rc2 #4455
• chore(release) - tag cometbft/api for v1.0.0-rc2 release #4456

For major release (v1.0.0) (not necessarily for alpha/RC)

• docs: An initial overhaul targeted for v1 release #302
• Update go and go built-in tutorial docs for v1 #2689
• docs: configuration manual #2351
• Consider adding a readme.md in the api module in v1
• config: document migration of config.toml file from v0.38.x to v1.x #2710
• Clarify the breaking nature of v1 upgrade #3416
• Concerns regarding Cometbft v1.0 upgrade #3834
• pbts: increase the default synchrony values to higher ones #4246
• chore(release) - tag cometbft/api for v1.0.0 release #4666
• chore(release): v1.0.0 #4656

### Tasks
- [X] Mark PebbleDB as the default backend (https://github.com/cometbft/cometbft/pull/4122)