docs: fix write-good.So/ThereIs/Weasel lint findings

Fixes the "obvious ones first" slice of #4042 (mara: do the obvious
ones first) -- 81 hits across write-good.So, write-good.ThereIs, and
write-good.Weasel, all in docs/. Each is a genuine sentence rewrite
(lead with the real subject instead of "There is/are", drop a
sentence-initial "So ", replace a vague intensifier), not a blind
regex substitution -- read every hit in its real file context before
touching it.

3 of the 81 hits were in CI-generated CLI docs (docs/tools/{hivectl,
swarmctl,forge}-cli.md) -- fixed at the clap #[arg(...)]/doc-comment
source in hivectl/src/cli.rs, swarmctl/src/main.rs, and
hive-forge/src/verbs/repo_add_collaborator.rs, then regenerated via
each crate's `markdown-docs` subcommand so CI's freshness check stays
green.

Verified: fresh vale re-run shows 0 remaining So/ThereIs/Weasel hits
and no new hits introduced (983->982, exactly the one incidental fix
this pass also picked up at docs/scheduler/observability.md:48).
cargo fmt --check and clippy clean on the three touched crates.

Remaining write-good backlog (Passive: 726, TooWordy: 207) is
judgment-heavy and left for a follow-up slice of #4042, not bulk-
rewritten here.

docs/turn-loop/mcp.md

@@ -46,7 +46,7 @@ preset (`AGENT_DEFAULT`) includes `messaging`, `meta`, `inbox`, and
   The graceful-stop turn takes the same post-turn compaction path as any
   other turn: if the context crossed the watermark the harness runs a
   notes-checkpoint turn and then `/compact`. Compacting before shutdown
-  keeps a later cold start cheap instead of re-uploading a huge transcript.
+  keeps a later cold start cheap instead of re-uploading a large transcript.
 - `ack_until(up_to)` — bulk-mark inbox rows handled: every row with
   broker id `<= up_to` is stamped as acked in a single UPDATE.
   Recipient-scoped (agents can only ack their own rows). Use when a
@@ -93,7 +93,7 @@ at_unix_timestamp?)`.
   payloads spill to `/agents/<self>/state/reminders/`. Pending count
   capped at 50 per agent (`HIVE_REMIND_MAX_PENDING_PER_AGENT`).
 
-There is no same-turn self-continue tool — see
+No same-turn self-continue tool exists — see
 [Turn outcomes](README.md#turn-outcomes) for why. Multi-step work rides
 `remind` for a durable self-wake, or an in-container todo wake
 (bash-task completion, forge notification, matrix activity) for work