docs(brief): align HTML technical brief with v1.1.0 physics

Rewrites sections 3-9 of week9_brief_latex.html to match the actual code:

Section 3 (Governing Physics):
- Eq 2: drop S_moisture(x,t) volumetric source term
- Eq 2c: replace rigid Dirichlet (theta_sat) with the partial-holiday
  parametrization theta_outer = f*theta_sat + (1-f)*theta_init,
  f = min(S_mag/S_ref, 1) — matches src/coupled_solver._holiday_theta_outer
- Eq notes describe the identifiability constraint S in [0, S_ref]
- Domain corrected from "2D axisymmetric" to "1D radial"; axial coord
  is mesh-only in v1.1.0

Section 4 (Inverse Problem):
- Replace fictional adjoint formulation (former Eq 7, 7a) with the
  actual golden-section line search (now Eq 7) that the code implements
- Misfit (Eq 6) reformulated as scalar single-point, not integral
- Add synthetic recovery accuracy table (0.2%, 0.0%, 0.9%) — matches
  the regression test in tests/test_remaining.py
- Surrogate description (Eq 8): correct feature set to the 6 actual
  parameters, correct N to 10,000 LHS samples, drop fictional
  4-8 min forward runtime

Section 5 (Monte Carlo): note the analytical Faraday shortcut in
_wl_from_params, distinguishing it from the full coupled solver

Section 7 (Escalation): update inverse description, correct domain
geometry to 1D radial, add test coverage row

Section 8 (Assumed Parameters): align all values with src/constants.py:
- D_THETA0 corrected from 1e-8 to 6e-11 (3 orders of magnitude)
- Add THETA_INIT, THETA_SAT, BETA_THETA, S_REF, ETA_MIXED, KMAT,
  DFOS noise sigma rows
- Drop the L-curve mention (we use a fixed lambda_reg = 1e-12)

Section 9 (Verification Status, renamed from Self-Review Gate):
- Replace 5 fictional reviewer personas with concrete verification
  rows tied to the actual codebase
- Explicitly mark adjoint formulation and 2D-z coupling as
  NOT IMPLEMENTED (gate-fail) — documented as future work

Section 1 hooks and Section 2 non-overlap kept; Section 2 stack
description updated to drop the adjoint claim.

Footer: bumped to 2026-04-28 and tagged v1.1.0.

Author: felipearocha