fix(projects): strip ephemeral proxy prefix from project_id

[GetsEclectic]

Problem (write-blocking)

In a sandbox whose git remotes are rewritten by an HTTP proxy to http://local_proxy@127.0.0.1:<port>/git/<owner>/<repo>, the <port> is ephemeral — a new port each session. _extract_project_id_from_git_remote keeps everything after the scheme, so the port lands in the project_id. Issues created in one session become unresolvable in the next, and every trc update/close/comment aborts with:

Cannot find project path for local_proxy@127.0.0.1:37849/git/<owner>/<repo>

(Hit in practice running trc inside Anthropic's Claude-on-the-web cloud sandbox, whose egress proxy rewrites every git remote this way.)

Root cause

_extract_project_id_from_git_remote (trace_core/projects.py) strips the URL scheme and .git suffix but otherwise returns the remainder verbatim, so the ephemeral local_proxy@<host>:<port>/git/ prefix becomes part of the project identity. The canonical JSONL is unaffected (project_id is dropped on export); only the per-machine SQLite-to-project-path mapping breaks.

Fix

After scheme stripping, detect the proxy signature and reduce it to <owner>/<repo>:

proxy = re.match(r"^local_proxy@[^/]+/git/(.+)$", url)
if proxy:
    url = proxy.group(1)

Anchored on the literal local_proxy@ userinfo so it cannot touch a real-world remote. Ports 37849 and 38291 both normalize to <owner>/<repo>; https://github.com/... and git@github.com:... remotes are unchanged.

Tests

tests/test_proxy_project_id.py:

1. Two proxy URLs differing only in port normalize to the same stable id.
2. Ordinary https / ssh GitHub remotes are unchanged.