fix: upgrade CI to Go 1.25 and document self-update feature

- Upgrade go-version from 1.24 to 1.25 in build.yml (required by go-selfupdate v1.6.0)
- Add kctl-tui update command and interactive startup check to README.md
- Document new features in CHANGELOG.md
- Update Go version requirement to 1.25+ in README.md and CONTRIBUTING.md
- Add Phase 5 (Self-update) to PLAN.md roadmap

.github/workflows/build.yml

@@ -19,7 +19,7 @@ jobs:
 
       - uses: actions/setup-go@v7
         with:
-          go-version: "1.24"
+          go-version: "1.25"
           cache: false
 
       - name: Tidy dependencies (generates/updates go.sum)
@@ -44,7 +44,7 @@ jobs:
 
       - uses: actions/setup-go@v7
         with:
-          go-version: "1.24"
+          go-version: "1.25"
           cache: false
 
       - name: Tidy dependencies (generates/updates go.sum)

CHANGELOG.md

@@ -6,6 +6,12 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/).
 
 ## [Unreleased]
 
+### Added
+- `kctl-tui update` — self-update command that downloads the latest release
+  from GitHub and replaces the running binary
+- Automatic update check on startup — prompts to update interactively when
+  a newer version is available
+
 ## [0.2.0] - 2026-08-09
 
 ### Added

CONTRIBUTING.md

@@ -13,7 +13,7 @@ go mod download
 
 ### Prerequisites
 
-- Go 1.22+
+- Go 1.25+
 - kubectl, k9s, tmux (or psmux on Windows)
 - An active Kubernetes cluster for integration testing
 

PLAN.md

@@ -77,6 +77,14 @@ is still open. For the full requirements, see [SPEC.md](SPEC.md).
 - [x] `--help` flag with full usage documentation.
 - [x] CHANGELOG.md, CONTRIBUTING.md, GitHub Issue/PR templates.
 
+## Phase 5 — Self-update (done)
+
+- [x] `kctl-tui update` — self-update command using `go-selfupdate` library.
+      Downloads the matching OS/arch asset from GitHub Releases and replaces
+      the running binary atomically.
+- [x] Interactive update check on startup — queries GitHub Releases in the
+      background, prompts the user to update when a newer version is found.
+
 ---
 
 ## Bugfix Sprint — between v0.2.0 and v0.3.0

README.md

@@ -107,7 +107,7 @@ go build -o kctl-tui ./cmd/kctl-tui
 sudo mv kctl-tui /usr/local/bin/
 ```
 
-Requires Go 1.22+.
+Requires Go 1.25+.
 
 ### 📦 Prebuilt binaries
 
@@ -203,11 +203,16 @@ kctl-tui                    # start the TUI (full navigation mode)
 kctl-tui --help             # show all commands and flags
 kctl-tui --version          # print version
 kctl-tui --verbose          # enable debug logging to stderr
+kctl-tui update             # update to the latest release
 kctl-tui doctor             # check if all tools, config and connections are OK
 kctl-tui config check       # validate ~/.kctl-tui/config.yaml
 kctl-tui panel --context=... --ns=... --team=...   # internal (called by tmux)
 ```
 
+When starting `kctl-tui` without a subcommand, a background check queries
+GitHub Releases for a newer version. If one is found, you are prompted to
+update interactively before the TUI starts.
+
 ## 🛠️ Development
 
 ```bash