Add nodes_hexagon and hexagon_more icons

[novykh]

Two icons the navigation redesign needs. Both currently render as empty tiles in the collapsed sidebar rail, because no equivalent mark exists in the set.

Export	Purpose
nodes_hexagon	The hexagon mark the design uses for Nodes. Two overlapping hexagon outlines.
hexagon_more	The "N more" overflow tile in the collapsed rail. Hexagon with an ellipsis.
hexagon_hollow	The up-one-level tile in the collapsed rail. Plain hexagon outline.
slo	The SLOs menu row. Dashed target/radar rings around a centre dot.
uptime	The Uptime menu row. Clock hands in a ring with a counter-clockwise restore arrow.

nodes_hexagon is added, not a replacement

The intent is for this to become the Nodes icon, but nodes_hollow is not swapped here. That asset has 17 call sites in cloud-frontend and one of them, useStaticTabs.js, feeds the legacy tab bar that renders when the new-navigation flag is off (roomNavigation.js picks between them on hasNavV2). Changing its artwork would alter a surface the flag exists to leave untouched.

A separate name also keeps the old mark available while the design is still being settled, and makes the switch a one-line change per call site rather than a repo-wide visual change.

hexagon_more differs from the Figma export

Two deliberate changes, both forced by how Icon renders:

It was a whole tile, not a glyph. The export carried the tile's own 23x23 bordered rect plus a drop shadow and an inner shadow. The rail draws that border itself and recolours it on selection, so a baked-in copy would double-draw and then stay grey while the surrounding tile turned green. No other asset in the set uses a <filter>.

It was two-tone - a translucent hexagon under lighter dots. Icon applies one colour to the whole SVG, so simply stripping the fills would have made the hexagon solid and swallowed the dots. The hexagon is drawn as a ring instead, outer and inner path under fill-rule="evenodd", which keeps the dots legible and lets the mark follow a single dynamic colour. A stroke would not work here, since the colour arrives as a fill.

The dot artwork is unchanged. The ring is a uniform 1 unit thick and the dots clear its inner edge by 1.1 units. viewBox is 4 8 16 16, a square crop centred on the hexagon, so the glyph is not distorted when given equal width and height.

hexagon_hollow

Supplied as-is; only the fill attributes are removed. Path data and winding are untouched.

Named for the shape rather than the direction, following the existing _hollow outline pairs, since the mark carries no directional cue of its own - the meaning comes from the tooltip the rail supplies ("Back to Nodes", "Back to node", and so on).

Five contexts render this tile - node, nodeLive, nodeLogs, alertInstance and dashboard - so five drill-in states currently show a blank square.

slo and uptime

Supplied as-is; only the fill attributes are removed, path data untouched. Both rows currently borrow unrelated glyphs - SLOs renders qualityOfServiceSolid and Uptime renders around_clock - which the navigation spec tracked as interim substitutes.

No traces icon is included. The design reuses the Logs glyph for that row, so it needs no new asset; the consuming app can point at the existing logs icon. Worth noting the spec describes that as placeholder reuse, so it may not be the final intent.

Conventions

Both follow src/components/icon/README.md: asset in ./assets, export added to ./iconsList.js, and no fill attribute so the consumer controls colour. Imports and exports are alphabetically placed; the list balances at 479/479.

Testing

97 suites / 473 tests green on node 22.22.0. The icon list balances at 482/482. No version bump included - releases here are their own commits.

Follow-up

Publishing this does not light up the rail on its own; cloud-frontend needs a released version and a package.json bump before RailUp/RailOverflow and the Nodes row can reference these names.

With this, every icon the navigation redesign was waiting on is in. Only traces remains, and it needs no asset - see above.