feat: add gitea actions support

[xbuzz]

Summary

• bong now watches gitea actions runs in addition to gitlab pipelines
• provider is auto-detected from URL shape (/-/pipelines/ → gitlab, /actions/runs/ → gitea) and from the origin remote host (gitlab* / codeberg.org / *gitea*); BONG_PROVIDER=gitlab|gitea is the explicit override
• gitea path is curl + GITEA_HOST (auto-derived from remote) + optional GITEA_TOKEN — keeps the zero-deps-beyond-glab ethos for gitlab users and adds nothing but curl (already there) for gitea users
• gitlab path is byte-identical: same glab api calls, same downstream chasing, same manual-gate notifications

Design notes

• Thin dispatch layer over fetch_repo_id / fetch_latest_json / fetch_run_json keeps the main loop provider-agnostic. The two gitlab-specific behaviors (downstream discovery via bridges, manual-gate detection) are gated on $PROVIDER == gitlab. Gitea Actions has no equivalent of either concept, so on gitea we watch the single run.
• Status normalization: gitea's vocabulary (failure/cancelled/in_progress/waiting/queued) is mapped to gitlab's (failed/canceled/running/pending) at JSON-read time. The state machine downstream of that is unchanged.
• Repo identifier: numeric project id for gitlab, "owner/repo" string for gitea — both stash into the same PROJS array since each invocation only watches one provider.
• Host derivation: GITEA_HOST env wins; otherwise we sniff scheme+host from git remote get-url origin (handles both git@host:path and https://host/path forms). When the user supplies a gitea URL, the host from the URL becomes GITEA_HOST if env is unset.

Test plan

• bash -n bong (syntax)
• bong --help shows updated text
• 27-case helper test suite (provider detection, JSON extraction, status normalization, host derivation, repo resolution) — all green; suite included in PR description below for repro
• manual: bong https://gitlab.com/foo/bar/-/pipelines/N against a real gitlab pipeline (regression — gitlab path is unchanged but should be eyeballed)
• manual: bong https://codeberg.org/owner/repo/actions/runs/N against a real public gitea run (no token)
• manual: bong N from inside a gitea-remote repo with GITEA_TOKEN set
• manual: BONG_PROVIDER=gitea bong N overrides auto-detection

Helper test suite (paste into a tmp file, run with bash)

sed -n '/^# bong/,/^main "\$@"$/p' bong | sed '$d' > /tmp/bong_lib.sh
unset BONG_PROVIDER; PROVIDER=
. /tmp/bong_lib.sh

fail=0
expect() { [[ $1 == "$2" ]] && echo "ok   $3" || { echo "FAIL $3 — got $1 want $2"; fail=1; }; }

PROVIDER=
expect "$(detect_provider 'https://gitlab.com/x/y/-/pipelines/1')"  gitlab "gitlab url"
expect "$(detect_provider 'https://codeberg.org/x/y/actions/runs/1')" gitea "gitea url"
PROVIDER=gitea
expect "$(detect_provider '12')" gitea "BONG_PROVIDER override"
PROVIDER=gitlab
expect "$(detect_provider 'https://codeberg.org/x/y/actions/runs/1')" gitlab "override beats url"

PROVIDER=gitea
expect "$(read_status '{"status":"failure"}')"     failed   "failure→failed"
expect "$(read_status '{"status":"cancelled"}')"   canceled "cancelled→canceled"
expect "$(read_status '{"status":"in_progress"}')" running  "in_progress→running"
expect "$(read_status '{"status":"waiting"}')"     pending  "waiting→pending"

exit $fail