feat(combat): port retail basic combat bar

Mount authored gmCombatUI, share one press/hold/release request state machine across DAT buttons and keybindings, and recover the exact 1.0s/0.8s power timing from matching retail x86. The same timer fixes jump charge, while ready-stance, response queueing, auto-repeat, layout binding, migration, and conformance coverage keep behavior architectural rather than panel-local.

Co-Authored-By: Codex <codex@openai.com>

docs/research/2026-07-11-retail-combat-bar-pseudocode.md

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+# Retail basic combat bar — port pseudocode
+
+## Sources
+
+- Named retail decomp:
+  - `gmCombatUI::RecvNotice_AttackHeightChanged` `0x004CC080`
+  - `gmCombatUI::RecvNotice_SetPowerbarLevel` `0x004CC0E0`
+  - `gmCombatUI::RecvNotice_DesiredAttackPowerChanged` `0x004CC110`
+  - `gmCombatUI::ListenToElementMessage` `0x004CC430`
+  - `gmCombatUI::RecvNotice_SetCombatMode` `0x004CC620`
+  - `ClientCombatSystem::Begin` `0x0056A460`
+  - `ClientCombatSystem::StartPowerBarBuild` `0x0056ADB0`
+  - `ClientCombatSystem::GetPowerBarLevel` `0x0056ADE0`
+  - `ClientCombatSystem::StartAttackRequest` `0x0056C040`
+  - `ClientCombatSystem::EndAttackRequest` `0x0056C0E0`
+  - `ClientCombatSystem::UseTime` `0x0056C1F0`
+  - `ClientCombatSystem::HandleAttackDoneEvent` `0x0056C500`
+  - `ClientCombatSystem::SetRequestedAttackHeight` `0x0056C8F0`
+- Matching retail executable disassembly (`acclient.exe` v11.4186 + PDB):
+  `ATTACK_POWERUP_TIME = 1.0` seconds and
+  `DUAL_WIELD_POWERUP_TIME = 0.8` seconds. The named pseudo-C's x87
+  expression had incorrectly collapsed the division operands.
+- LayoutDesc `0x21000073` (`gmCombatUI`), cross-checked against the retail UI
+  layout dump. Root is 610×90; basic page is `0x1000005C`, desired-power
+  scrollbar is `0x1000004F`, embedded meter is `0x10000050`, and the
+  high/medium/low buttons are `0x10000057/58/59`.
+- Interpretation cross-checks: ACE combat request/power fields and the
+  holtburger `DesiredAttackProfile -> attack_request` wire path summarized in
+  `docs/research/deepdives/r02-combat-system.md`.
+
+## Initial state
+
+```text
+combatMode = NonCombat
+buildInProgress = false
+attackRequestInProgress = false
+attackServerResponsePending = false
+requestedAttackPower = 0
+requestedAttackHeight = Medium
+desiredUiPower = 0.5
+repeatAttacking = false
+```
+
+## Panel visibility
+
+```text
+when combat mode changes:
+    if AdvancedCombatUI:
+        hide gmCombatUI
+    else if mode == Melee:
+        set root state Melee (0x10000003)
+        show gmCombatUI
+    else if mode == Missile:
+        set root state Missile (0x10000004)
+        show gmCombatUI
+    else:
+        hide gmCombatUI
+```
+
+The current acdream port binds the basic page because the persisted gameplay
+default has `AdvancedCombatUI = false`. The separate advanced-combat surface is
+still tracked by divergence row AP-110.
+
+## Press / charge / release
+
+```text
+SetRequestedAttackHeight(height):
+    changed = requestedAttackHeight != height
+    requestedAttackHeight = height
+    if changed OR no attack request is active:
+        StartAttackRequest()
+
+StartAttackRequest():
+    target = current attack target
+    if target is not attackable: report no target and stop
+    attackRequestInProgress = true
+    requestedAttackPower = 1
+    stop jump and movement
+    currentBuildIsAutomatic = false
+    if player is ready and no build is active:
+        StartPowerBarBuild()
+
+StartPowerBarBuild():
+    buildInProgress = true
+    buildStartTime = currentTime
+    displayedPower = 0
+
+GetPowerBarLevel():
+    if no build: return 0
+    duration = current stance is DualWieldCombat ? 0.8 seconds : 1.0 second
+    return clamp((currentTime - buildStartTime) / duration, 0, 1)
+
+EndAttackRequest(height, explicitPower = -1):
+    if no attack request: stop
+    attackRequestInProgress = false
+    current = GetPowerBarLevel()
+    requestedAttackPower = explicitPower >= 0
+        ? explicitPower
+        : min(desiredUiPower, current)
+    if a prior attack is awaiting the server:
+        queue this power for AttackDone
+    else if desiredUiPower <= current OR repeat attack is active:
+        ExecuteAttack(height)
+    otherwise:
+        UseTime commits on its next eligible tick at requestedAttackPower
+
+UseTime():
+    if a build is active:
+        current = GetPowerBarLevel()
+        publish current to meter
+        if request was released AND current >= requestedAttackPower:
+            publish min(requestedAttackPower, current)
+            if build is not automatic: ExecuteAttack(requestedHeight)
+            else stop automatic build
+```
+
+## UI messages
+
+```text
+mouse-down high/medium/low:
+    SetRequestedAttackHeight(High/Medium/Low)
+
+mouse-up high/medium/low:
+    EndAttackRequest(the height, -1)
+
+desired-power slider changed with integer position 0..1000:
+    desiredUiPower = clamp(position * 0.001, 0, 1)
+
+attack power increase/decrease action:
+    move desiredUiPower by one sixth, clamped to 0..1
+```
+
+Both keyboard and retained buttons therefore use one transition-based attack
+controller. A one-shot click/keypress is not sufficient: down begins charging,
+up ends the request.