hive-forge: infer active repo from cwd's git remote, demote HIVE_FORGE_REPO

docs/tools/forge.md

@@ -7,8 +7,10 @@ as a proper Rust binary). Use it instead of ad-hoc curl pipelines.
 ## Credentials and repo defaults
 
 - Credentials: `$HYPERHIVE_STATE_DIR/forge-token`
-- Default repo: `$HIVE_FORGE_REPO`
-- Per-invocation override: global `-r/--repo` flag
+- Active repo resolves, highest priority first: global `-r/--repo` flag
+  > the `origin` remote of the cwd's git checkout > `$HIVE_FORGE_REPO`
+  (last-resort override, unset by default) > a hard error. No single
+  repo is assumed by default — see `client::Client::from_env`.
 
 ## Verbs
 
@@ -207,7 +209,8 @@ and print its URL. Key flags:
 - `--description <TEXT>` — repo description
 
 **`repo-add-collaborator <user>`** — grant a forge user access to the
-active repo (`-r`/`HIVE_FORGE_REPO`). Companion to `repo-create`. The
+active repo (see the repo-resolution chain above). Companion to
+`repo-create`. The
 `--permission` flag accepts `read` / `write` (default) / `admin`.
 `hive-c0re` uses this internally when an agent's config repo is
 initialised.