docs(roadmap): add Phase 8 — Analysis Depth, renumber language expansion to Phase 7 (#706)

* docs(roadmap): add Phase 7 — Analysis Depth (depth over breadth)

Insert new Phase 7 between Phase 6 (Native Analysis Acceleration) and
the former Phase 7 (now Phase 8 — Expanded Language Support). All
subsequent phases renumbered 7→8 through 13→14 with cross-references
updated throughout.

Phase 7 targets raising caller coverage from 29% to ≥70% for TS/JS
projects via seven sub-phases: TypeScript-native type resolution
(ts.createProgram), inter-procedural type propagation, field-based
points-to analysis (ACG/Jelly-inspired), barrel file resolution,
enhanced dynamic dispatch (CHA+RTA), precision/recall CI gates, and
reaching definition analysis (PDG foundation).

Only optional runtime dependency: `typescript` for sub-phase 7.1.
All other sub-phases use existing tree-sitter infrastructure.

Motivated by the architecture audit (v3.4.0) which identified 29%
caller coverage as the single highest-impact limitation. Research
grounded in Joern CPG, Jelly, ACG (99% precision/91% recall), and
the TS compiler API.

* docs(roadmap): renumber Phase 7/8 — language expansion before analysis depth

Language expansion (now Phase 7) is already underway; analysis depth
(now Phase 8) benefits more languages when it lands after breadth.
Swapped sections, renumbered sub-phases, and updated cross-references.

Author: carlos-alm