feat(berths): NocoDB-aligned dropdown enums + dual-unit auto-fill

Pull verbatim SingleSelect choices from NocoDB Berths via MCP and lock
them into BERTH_*_OPTIONS / _TYPES in lib/constants.ts: Side Pontoon
(10 values), Mooring Type (5), Cleat Type (2), Cleat Capacity (2),
Bollard Type (2), Bollard Capacity (2), Access (5), Area (A–E), Bow
Facing (4-value UX-only constraint over a SingleLineText). Power
Capacity / Voltage stay numeric inputs (NocoDB stores Number).

Add `toSelectOptions()` mapper for shadcn `<Select>` `{value,label}`
pairs.

Wire every berth dropdown — both the modal form and the inline-edit
detail tabs — to `<Select>`. Inline `EditableSpec` gains
`selectOptions` for the variant and `linkedUnit { field, multiplier }`
to auto-patch the metric column on save (× 0.3048 for ft→m on length,
width, draft, nominal boat size, water depth).

Promote nominal boat size + tenure type from read-only `<SpecRow>` to
`<EditableSpec>` so reps can edit them. Tenure type currently uses the
validator's `'permanent' | 'fixed_term'` set; will swap to per-port
configurable list once Vocabularies admin lands (Wave 5).

Mobile berth cards: replace status-coloured stripe with
`mooringLetterDot()` so it groups by dock letter; status conveyed by
the existing pill below. Berth detail header: "{Letter} Dock" chip
instead of bare "A" / "B" text. Berth area filter: `<Select>` over
A/B/C/D/E (renamed to "Dock"). Documents tab gets a one-paragraph
explainer disambiguating the spec PDF from deal documents (Interests
tab).

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

src/components/berths/berth-documents-tab.tsx

@@ -162,6 +162,12 @@ export function BerthDocumentsTab({ berthId }: { berthId: string }) {
 
   return (
     <div className="space-y-6">
+      <p className="text-sm text-muted-foreground">
+        Berth-spec PDF: the dimensional drawing or surveyor sheet for this slip.
+        Versioned so a misparse can be rolled back. For documents tied to a
+        prospect on this berth (EOI, contract, etc.), open the matching deal
+        in the Interests tab.
+      </p>
       <Card>
         <CardHeader className="flex flex-row items-center justify-between pb-3">
           <CardTitle className="text-sm font-medium">Current PDF</CardTitle>