feat: support multiple Slack/GitHub project integrations with TUI

[markhallen]

Summary

• Add multi-project support: multiple Slack workspaces can be paired with different GitHub repositories, each with its own credentials
• Interactive TUI (bin/slack-gh-config / rake config) for adding, editing, removing, and listing project integrations
• Encrypted config file (AES-256-GCM + PBKDF2) at .config/projects.enc — no database required
• Incoming Slack requests routed by team_id with automatic env var fallback for full backward compatibility

New files

• lib/config/encryption.rb — AES-256-GCM encryption with PBKDF2 key derivation (Ruby stdlib only)
• lib/config/project_config.rb — Multi-project config model with CRUD, encrypted file I/O, team_id lookup
• lib/cli/tui.rb — Interactive TUI using tty-prompt/tty-table
• bin/slack-gh-config — CLI entry point
• Tests: 31 new tests across encryption, config, TUI, and multi-project integration

Modified files

• app.rb — Config loading on startup, team_id extraction, token resolution with fallback
• Gemfile — Added tty-prompt, tty-table
• Rakefile — Added rake config task
• README.md — Multi-Project Setup section, updated features/env vars/structure/security
• CLAUDE.md — Updated architecture and commands

Closes #34

Test plan

• bundle exec rake ci passes (70 tests, 136 assertions, RuboCop clean)
• Existing tests pass unchanged (backward compatibility)
• Run bundle exec rake config to verify TUI flow (add/list/edit/remove projects)
• Verify encrypted config file is created at .config/projects.enc and is not readable without passphrase
• Test multi-project routing: set CONFIG_PASSPHRASE, start server, send request with matching team_id
• Test fallback: remove config file, verify app works with env vars only

🤖 Generated with Claude Code

[Copilot]

Pull request overview

Adds support for configuring and routing multiple Slack workspace ↔ GitHub integrations, backed by an encrypted on-disk config and managed via an interactive terminal UI, while preserving env-var fallback for backward compatibility.

Changes:

• Introduces encrypted multi-project configuration storage and lookup by Slack team_id.
• Adds an interactive TUI + CLI entrypoint (and rake config) to manage project integrations.
• Updates Sinatra request handling to resolve tokens per-project with env-var fallback; adds tests covering multi-project routing and config/encryption.

Reviewed changes

Copilot reviewed 13 out of 15 changed files in this pull request and generated 7 comments.

Show a summary per file

File	Description
app.rb	Loads encrypted project config on startup; resolves credentials by team_id with fallback
lib/config/encryption.rb	AES-256-GCM + PBKDF2 encryption/decryption utilities
lib/config/project_config.rb	Multi-project model with CRUD, encrypted file I/O, team lookup
lib/cli/tui.rb	TUI for adding/editing/removing/listing projects
bin/slack-gh-config	CLI entry point for the TUI
Rakefile	Adds rake config task
Gemfile / Gemfile.lock	Adds TTY dependencies for TUI
README.md	Documents multi-project setup, config encryption, and usage
CLAUDE.md	Updates architecture/commands documentation
test/test_app.rb	Updates expectation for new missing-credentials error message
test/test_multi_project.rb	Adds integration tests for routing by team_id and fallback
test/config/test_encryption.rb	Adds encryption unit tests
test/config/test_project_config.rb	Adds project config unit tests
test/cli/test_tui.rb	Adds TUI flow tests with a mock prompt

Comments suppressed due to low confidence (1)

lib/config/project_config.rb:62

• update_project applies updates without re-validating invariants (non-empty name/slack_team_id, uniqueness of name and slack_team_id). This allows edits that can break routing (e.g., blank/duplicate team IDs) or create duplicate names. Add the same validations used in add_project (plus duplicate checks that exclude the current record) before persisting changes.

    def update_project(name, attrs)
      project = find_by_name(name)
      raise ArgumentError, "Project '#{name}' not found" unless project

      attrs.each do |key, value|
        sym_key = key.to_sym
        project[sym_key] = value if project.key?(sym_key)
      end
      project