but branch list improvements

Enhance branch listing with richer filtering and options:
- support remote/local/all, ahead and review flags, JSON output
  parameter stubs
- fetch review info only when --review is requested
- filter applied stacks and their heads when a name filter is
  provided
- remove branches that belong to applied stacks early
- apply name and dependabot filters and more robust retention logic

Refactor list signature and internal flow to build and filter the
branch list incrementally, improving performance and correctness.
more
more
Add --check to "but branch list" to test mergeability

Add a --check flag to the branch list command that computes whether each listed branch can be cleanly merged into the upstream target branch. This introduces a merge status map propagated into list rendering (JSON and table views) and a new helper check_branches_merge_cleanly that uses repository/Gix APIs to detect merge bases and whether trees merge cleanly.

The change updates branch output structs to include merges_cleanly, wires the new check option through CLI parsing, prints a brief stderr message when checking, and appends a ✓/✗ indicator next to the commits-ahead column in table output. It also handles fallback behavior when references or merge bases are missing by treating them as conflicts or skipping missing commits.
Move merge check indicator to left and enable by default

Move the merge status indicator (✓/✗) to the left of branch names in the branch list output so the check appears immediately before the branch/tree prefix. Also change the CLI flag semantics so checking merges is enabled by default and controlled with --no-check instead of requiring --check. This improves the readability of branch rows and makes safe merge-checking the default behavior.

Author: schacon

Cargo.lock

@@ -50,11 +50,20 @@ gitbutler-command-context.workspace = true
 gitbutler-reference.workspace = true
 gitbutler-oplog.workspace = true
 
+git2.workspace = true
+async-openai.workspace = true
 posthog-rs = { version = "0.3.7" }
 serde.workspace = true
 tokio = { workspace = true, features = ["rt-multi-thread", "io-std"] }
 strum = { version = "0.27", features = ["derive"] }
-clap = { workspace = true, features = ["env", "wrap_help", "color", "error-context", "usage", "suggestions" ] }
+clap = { workspace = true, features = [
+    "env",
+    "wrap_help",
+    "color",
+    "error-context",
+    "usage",
+    "suggestions",
+] }
 clap_complete = "4.5.60"
 chrono.workspace = true
 bstr.workspace = true
@@ -76,7 +85,12 @@ tracing-forest.workspace = true
 ratatui = "0.29.0"
 crossterm = "0.29.0"
 cli-prompts = "0.1.0"
-minus = { version = "5.6.1", default-features = false, features = ["static_output", "search"] }
+minus = { version = "5.6.1", default-features = false, features = [
+    "static_output",
+    "search",
+] }
+unicode-width = "0.1"
+term_size = "0.3"
 
 [dev-dependencies]
 but-core = { workspace = true, features = ["testing"] }