Add go command for existing worktrees

[cmalherbe-atlassian]

Problem

Treehouse can create or lease worktrees, but there is no quick way to see existing sessions and jump back into one from an arbitrary directory. Users need a navigation command that works globally across managed pools, not just from the repository that owns a specific pool.

Implementation summary

• Adds treehouse go [target].
• With no target, lists all existing Treehouse-managed worktrees under the user-level Treehouse root and prompts for a numeric selection.
• With a target, resolves a unique existing worktree by exact path, basename, Treehouse state name, or unique substring.
• Opens a shell in the selected worktree using the same shell spawning path as treehouse get.
• Does not acquire a new worktree and does not return the selected worktree to the pool when the shell exits.
• Reuses Treehouse state/list primitives instead of adding another state source.
• Shows the interactive choices in a table with status, project, and location.
• Truncates long project names to keep the table readable while leaving full locations visible.

Examples

Interactive navigation from anywhere:

treehouse go

Example output:

🌳 Treehouse worktrees:
#   Status       Project               Location
--  -----------  --------------------  --------
1   [available]  jira                  ~/.treehouse/jira-abc123/1/jira
2   [leased   ]  treehouse             ~/.treehouse/treehouse-def456/2/treehouse  (held by claude)
3   [available]  otherrepo-with-a-...  ~/.treehouse/otherrepo-with-a-very-long-name-c2a333/1/otherrepo-with-a-very-long-name
Choose a worktree:

Direct navigation by basename:

treehouse go jira

Direct navigation by unique substring:

treehouse go auth-refactor

Direct navigation by path:

treehouse go ~/.treehouse/treehouse-def456/2/treehouse

Ambiguous targets fail clearly instead of choosing silently:

Error: target "tree" is ambiguous; matches: t1 (...), t2 (...)

Validation

• go test ./internal/pool ./cmd -run 'Test(ListNavigation|ResolveNavigation|Go)'
• go test ./cmd -run TestGoInteractiveListsGlobalWorktreesAndOpensSelection
• go test ./cmd -run 'Test(TruncateTableCell|GoInteractiveListsGlobalWorktreesAndOpensSelection)'
• go test ./...
• GOOS=windows go build ./...
• Lightweight code review by subagent for the changed Go files.

Risks

• The project label is derived from the managed pool directory name. This mirrors Treehouse's existing pool layout and strips the generated hash suffix for readability.
• The command opens an interactive shell, so automated tests use the existing test shell shim rather than launching a real user shell.

Follow-ups

• Consider adding a non-interactive --json or --plain list mode if scripts need to consume the global session list later.
• Consider optional path truncation if the location column becomes too wide in terminals.