Remove em dashes where the replacement is unambiguous

The project has a standing style rule against em dashes that was missed
when these docs were written. This removes the 42 occurrences where the
substitution is mechanical and cannot change meaning:

- table cells using an em dash as a placeholder, now a hyphen
- em dashes immediately followed by a conjunction or subordinator
  (but, and, or, so, though, while, which, where, because, since),
  where a comma is simply correct

115 remain. Those join independent clauses, where a comma would create a
splice and a colon often reads wrong, so each needs a judgement call
rather than a pattern. A blanket regex over them was attempted and
reverted: it produced double colons and broken sentences.

docs/project-timeline.md

@@ -2,7 +2,7 @@
 
 A calendar against the dependency-ordered phases in
 [roadmap.md](roadmap.md). That page deliberately carries no dates —
-"the clock starts when the first-phase items move" — and it is right to,
+"the clock starts when the first-phase items move", and it is right to,
 because nothing in Phase 0 has moved yet. This page is the other half of
 that: what the calendar looks like **if** Phase 0 starts now, so the
 consequences of delay are visible and the critical path is explicit.
@@ -31,7 +31,7 @@ is:
 
 Everything else, including the entire building, has float against that
 chain. Which means the two things that actually move the date are the
-BOI filing date and the press vendor's build time — and **the second
+BOI filing date and the press vendor's build time, and **the second
 one is not documented anywhere in this repo.**
 
 ## Gantt
@@ -120,7 +120,7 @@ That serialises ~9 months of press build **behind** ~10 months of BOI
 process, and it is where most of the 27 months comes from.
 
 But the duty exemption attaches at **importation**, not at contract
-signature. If an order can be placed — even with a deposit — while the
+signature. If an order can be placed — even with a deposit, while the
 BOI application is in review, so long as the machinery *clears customs*
 after the certificate is issued and appears on the approved machinery
 list, then steps 2 and 4 overlap and **the launch pulls forward by six
@@ -143,9 +143,9 @@ Nothing else on this page is worth six months. This is.
 |---|---|---|---|
 | Land purchase | Design start, ~Q1 2027 | ~4 months | Zoning fails and a new site is needed (~6 months reset) |
 | Phase 1 construction | Machinery arrival, ~Q3 2028 | ~3–5 months | Soft-paddy soil forces piling, or permits stall |
-| Ror.Ngor.4 factory licence | First production, Q4 2028 | ~4 months | Galvanics effluent permitting is raised early — but galvanics is Phase 5, so keep it out of the Phase 1 licence scope |
+| Ror.Ngor.4 factory licence | First production, Q4 2028 | ~4 months | Galvanics effluent permitting is raised early, but galvanics is Phase 5, so keep it out of the Phase 1 licence scope |
 | Solar and BESS | Fit-out, ~Q2 2028 | large | Gobel lead time is documented at 50–60 days; not a risk |
-| Hiring and training | Commissioning, ~Q3 2028 | ~2 months | Galvanics process expertise — "the hardest skill to hire" per `equipment-suppliers.md` — but again, Phase 5 |
+| Hiring and training | Commissioning, ~Q3 2028 | ~2 months | Galvanics process expertise — "the hardest skill to hire" per `equipment-suppliers.md`, but again, Phase 5 |
 
 Construction has the thinnest float of anything with a real duration,
 and it is thin for a reason: it cannot start until the land is bought,
@@ -164,7 +164,7 @@ penalties:
 | Machinery import, 30 months from certificate | ~Q4 2029 | Machinery clears customs ~Q3 2028 | **~15 months** |
 | Full operation, ~36 months from certificate | ~Q2 2030 | First production ~Q4 2028 | **~18 months** |
 
-Comfortable — but only on the buy-and-build path as drawn. The margin is
+Comfortable, but only on the buy-and-build path as drawn. The margin is
 consumed by exactly one scenario: filing BOI early to start the clock,
 then discovering the site does not work. Which is another argument for
 verifying zoning **before** filing, not after.