feat(settings): tabbed MCP install instructions with Claude Code flow

Replace the hand-edit-JSON instructions in Settings → API Keys with a
tabbed UI (Claude Code / Claude Desktop / Other). The Claude Code tab
leads with the `claude mcp add` command, pre-filled with FABLE_URL and
the most recently generated API key, plus copy-to-clipboard buttons on
every snippet. Recommend `uv tool install` or `pipx install` over bare
`pip install` so fable-mcp reliably lands on PATH under PEP 668.

Also fix incorrect priority values in fable-mcp tool docstrings — the
enum is `none|low|medium|high`, not `low|normal|high`.

DRY pass: extract shared `copyToClipboard()` helper used by both
`copyApiKey` and the new snippet buttons; reuse existing
`btn btn-secondary btn-sm` for the copy buttons instead of a bespoke
class.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

fable-mcp/pyproject.toml

@@ -4,7 +4,7 @@ build-backend = "hatchling.build"
 
 [project]
 name = "fable-mcp"
-version = "0.2.4"
+version = "0.2.5"
 description = "MCP server for Fabled Assistant"
 requires-python = ">=3.12"
 dependencies = [