Three structural results organise the account. \textbf{(i)} In the PVT $(L,T)$ system every SP constant is a pure power of the single measure $\pi\equiv T/L$: $c_{\mathrm{std}}=\pi^{-1}$, $G=\pi$, $e=\pi^{2}$, $k_B=\pi^{3}$, $h=\pi^{4}$ --- the \emph{$\pi$-ladder}, in which the exponent counts the internal angular measures a quantity carries.  The isotropic projection freezes the three internal angles to $90^\circ$ ($\pi\to1$) and lowers one length grade per areal velocity ($L^2/T\mapsto L/T$); the removed length is re-imported as the law's constant. Each of the three non-inertial force laws purchases exactly one such length, reproducing the four-plus-three architecture.  Gravitation is a \emph{volume} projection, electromagnetism an \emph{area} projection, organised in a single projection grammar. We further argue that treating the areal invariant $L^2/T$ as the linear constant $c=L/T$ is a category error that injects an uncancelled transcendental residue into SP; that measurement is inherently the areal (triangular) form $L^2/T$, so quantisation is a property of the \emph{measurement}, not of the continuous substrate; and that gravitational singularities are the shadow of freezing the live reciprocal pair $(c,G)=(\pi^{-1},\pi)$ into two independent numbers. All dimensional and numerical identities are verified symbolically. Every substantive statement is marked \derived, \posited{} or \opn.