feat(ui): AtlasAgentInterface — observe/act named-intent control channel (D-226, T-971)

D-226 layer 4, rebuilt against the post-D-255 stepped Atlas after the
Phase-1 reconciliation (the original intent list targeted the retired
continuous-zoom viewer). Eleven intents, each backed by the exact
production handler a click calls — select/open for systems and bodies
(extracted shared by-id tails so click and intent paths are one code
path), scroll_rung, reset_view, back, open/close_atlas, set_overlay —
plus two new first-class capabilities: jump_to_center (the fixed-center
revisit pattern proven by five eyeball drivers, via a new
StepCanvasViewer.jump_to seam that reuses _scroll_rung's exact request
tail — same extent cap, same cache keys) and get_current_canvas_summary
(allocation-light reads off the raw wire dict, courses-by-class,
draw-matched settlement dedup — no PNG decode). Contract shape: dumb
AtlasAgentBridge autoload holding the app handle (untyped per the
parse-order rule), all logic in the static AtlasAgentInterface class.
observe() is side-effect-free: current state + a generic Control-walk
affordance tree. In-process consumers only this ticket (documented);
the committed reference driver (atlas_agent_driver.gd, InputSwallower +
settle-until-ready from the T-1157 inventory) replaces the scratch
eyeball drivers as the sanctioned headless-drive pattern.
select_city/open_regional dropped with recorded rationale (no
settlement hit-test affordance exists post-D-255) — diff on the ticket.
33 new tests across three suites.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

client/scripts/autoloads/atlas_agent_bridge.gd

@@ -0,0 +1,29 @@
+extends Node
+
+## AtlasAgentBridge (T-971, D-226 item 4) — the ONE stable, always-reachable
+## handle onto the live AtlasApp instance, so an in-process agent driver (a
+## `-s` SceneTree script, a gdUnit suite, the T-1157 capture harness) has a
+## fixed autoload address to start from instead of walking the scene tree
+## itself.
+##
+## Deliberately a DUMB holder, per CLAUDE.md's autoload parse-order rule: an
+## autoload script compiles before global `class_name` scripts are
+## registered, so referencing a `class_name` type (AtlasApp, AtlasAgent
+## Interface) at this file's top level or in _ready() would fail to
+## resolve. This file therefore declares its field UNTYPED (`var
+## current_app = null`) and does nothing else — every actual observe()/act()
+## call is a STATIC method on AtlasAgentInterface
+## (res://ui/implant/apps/atlas/atlas_agent_interface.gd), loaded via
+## `load()` inline at call time by whatever script needs it (the same
+## deferred-load pattern game_state.gd/sim_bridge.gd already use for their
+## own class_name-typed fields). This autoload carries no logic of its own
+## to keep that boundary clean — "dumb holder delegating to a static class",
+## per the ruling.
+##
+## `current_app` is set by AtlasApp.on_install() (the same lifecycle point
+## ImplantApp guarantees runs once, before any HudGroups open event) and
+## cleared by nothing — an installed app instance lives for the process
+## lifetime, matching every other ImplantApp subclass's own singleton-per-
+## process posture (HudGroups.register() itself assumes one instance per
+## app_path).
+var current_app = null  # AtlasApp, set by atlas_app.gd's on_install()