extend build-info bake to name + tagline + repository

User asked for the rest of the pubspec-derived strings to share the
same path the version went down. gen-build-info now also writes
`clideName`, `clideTagline`, `clideRepository` to
lib/src/build_info.g.dart from pubspec.yaml. Added a `tagline:`
field to pubspec for the short user-facing line (the welcome
subtitle, future web meta) — pubspec stays the single source of
truth for every name/tagline/version/repository string the app
shows.

Consumers swept:
* welcome banner ('clide' / 'IDE for Claude Code CLI') and status
  line version label read from the constants.
* app.dart WidgetsApp title + project-switcher label use clideName.
* clide_column_hat uses clideName for the empty-projects fallback.

Co-Authored-By: Claude <noreply@anthropic.com>

pubspec.yaml

@@ -15,6 +15,11 @@ description: >-
 publish_to: none
 version: 2.1.0
 repository: https://github.com/postmeridiem/clide
+# Short user-facing tagline (the welcome subtitle, web meta
+# description, etc.). Baked into lib/src/build_info.g.dart by
+# `make gen-build-info` — pubspec.yaml is the single source of
+# truth; nothing else duplicates this string in source.
+tagline: "IDE for Claude Code CLI"
 
 # Pre-push line-coverage floor. Ratchets up only — see D-66.
 # Reading: `awk -F: '/^coverage_floor:/ {gsub(/ /,"",$2); print $2}' pubspec.yaml`.