Fix agent resume, command injection and GitHub CLI probing in terminals

[0x92]

Description

Three independent fixes to agent terminals. None of them is a feature; all three are about a failure that looks like the agent misbehaving.

1. Resumed sessions came back empty. Every spawned terminal inherited the launching process's environment wholesale. When Pane itself is started from inside a Claude Code session — a terminal, a script, a dev run — that includes CLAUDE_CODE_CHILD_SESSION, and Claude Code responds by switching transcript persistence off ("Transcript saving is off — inherited CLAUDE_CODE_CHILD_SESSION marker"). Nothing is written, so the next claude --resume <id> fails with "No conversation found with session ID" and the pane comes back blank after a restart, with nothing on screen explaining why. Those markers are now stripped at spawn: every terminal Pane starts is a new top-level session, so the launching agent's identity is always wrong to pass on.

2. The resume command sometimes ran as laude. A terminal that has just printed its prompt can lose the first character it is given — ConPTY switches input modes around the prompt, and a resize arriving in the same moment makes it likelier. The command then fails as "command not found" and reads as if Pane sent nonsense. It shows up on restart, exactly when a session is trying to resume its agent. The command is now preceded by a byte that costs nothing either way: Ctrl-U clears the input line, and at a fresh prompt there is nothing to clear. Whatever the shell swallows is not part of the command; the command follows 60 ms later.

3. Two red console lines per session, per refresh, on machines without gh. PR enrichment ran gh pr list on every git status refresh regardless of whether the GitHub CLI exists. Availability is now probed once per execution context — keyed by WSL distribution, since the host and a distro have separate PATHs — and the lookup itself is silent. A repository with no GitHub remote, or an unauthenticated gh, is a normal state for a local project, not something to shout about.

Notes

Both new modules (agentSessionEnv, terminalInjection) sit next to terminalPanelManager rather than inside it, so they can be unit-tested without pulling in the database singleton it depends on.

Type of Change

• Bug fix (non-breaking change which fixes an issue)

Checklist

• I have read the CONTRIBUTING.md guidelines
• My code follows the code style of this project
• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• My changes generate no new warnings
• I have added tests that prove my fix is effective or that my feature works
• New and existing unit tests pass locally with my changes
• I have run pnpm typecheck and pnpm lint locally
• I have tested the Electron app locally with pnpm electron-dev

Critical Areas Modified

• State management/IPC events

Additional Notes

Tests: 5 for environment stripping, 4 for the injection sequence, and the existing PR-enrichment tests now count gh pr list lookups rather than every command, since the availability probe adds one.

Verified in the running app: a session whose agent had been resumed after a restart, on a host where Pane itself was launched from inside a Claude Code session.