feat: complete MVP — all 14 tasks done

- Task 13: Full documentation (README, INSTALLATION, USAGE, ARCHITECTURE)
- Task 14: Release prep (CHANGELOG, RELEASE_CHECKLIST)
- Update PROJECT_STATE.md to reflect 100% completion

RELEASE_CHECKLIST.md

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+# Release Checklist
+
+## Pre-Release
+
+- [ ] All tests pass: `make test`
+- [ ] Test coverage is adequate: `make test-coverage`
+- [ ] `go vet` passes: `make vet`
+- [ ] Lint passes: `make lint`
+- [ ] All platforms build successfully: `./build.sh`
+- [ ] `CHANGELOG.md` is up to date
+- [ ] Version is updated in source
+- [ ] Documentation is current
+
+## Testing
+
+- [ ] Integration tests pass: `go test ./test/integration/`
+- [ ] Manual smoke test all commands:
+  - [ ] `hostkeeper add`
+  - [ ] `hostkeeper list`
+  - [ ] `hostkeeper connect`
+  - [ ] `hostkeeper edit`
+  - [ ] `hostkeeper delete`
+  - [ ] `hostkeeper export`
+  - [ ] `hostkeeper import`
+  - [ ] `hostkeeper tui`
+  - [ ] `hostkeeper version`
+  - [ ] `hostkeeper completion`
+
+## Release
+
+- [ ] Tag the release: `git tag v1.0.0`
+- [ ] Push tags: `git push origin --tags`
+- [ ] Build release binaries: `./build.sh`
+- [ ] Verify checksums in `build/checksums.txt`
+- [ ] Create GitHub release with binaries attached
+- [ ] Post-release announcement (if applicable)
+
+## Post-Release
+
+- [ ] Update PROJECT_STATE.md
+- [ ] Start next milestone planning