Add mobile LSP hover and signature requirements

PRODUCT.md

@@ -18,7 +18,7 @@ The user opens Vim or Neovim over SSH and tolerates bindings, ex commands, split
 
 ## Feature-complete boundary
 
-Feature-complete means good enough to be the default tool for real small-to-medium code changes over SSH from an iPhone. It includes: protocol/socket + `mimctl`, deterministic replay, UTF-8/cell-width-correct editing, mobile leader/symbol input, narrow transient panels, file tree/search, read-only git workbench, build/test output, terminal escape hatch, Tree-sitter, LSP diagnostics/navigation/actions, and local Pi/tool context through the socket.
+Feature-complete means good enough to be the default tool for real small-to-medium code changes over SSH from an iPhone. It includes: protocol/socket + `mimctl`, deterministic replay, UTF-8/cell-width-correct editing, mobile leader/symbol input, narrow transient panels, file tree/search, read-only git workbench, build/test output, terminal escape hatch, Tree-sitter, LSP diagnostics/navigation/actions, viewport-aware hover/signature help, parameter navigation inside calls, and local Pi/tool context through the socket.
 
 ## Build shape
 

REQUIREMENTS.md

@@ -27,6 +27,8 @@ Rows are redgate TSV requirements: `ring<TAB>id<TAB>summary [tag]`.
 0	001	Buffer and rendering code SHALL preserve UTF-8 boundaries and terminal cell width semantics. [core]
 1	002	Tree-sitter syntax highlighting SHALL be built in with source-patched language tables. [syntax]
 1	003	LSP support SHALL be built in and spawn existing language servers without installing them. [lsp]
+1	004	LSP hover and signature help SHALL use viewport-aware presentation that remains usable on narrow terminals. [lsp]
+1	005	When syntax or LSP data is available, `mim` SHALL provide mobile-friendly navigation between parameters in function calls. [lsp]
 
 ## repo