feat(client): introduce Michroma font and implant UI theme (#517)

Add Michroma-Regular.ttf (OFL license) as the game font. Create
FontVariation with +1px tracking and a global Theme resource with
cyan-white (#E0F7FA) implant text color. Wire theme into project.godot
so all Label/RichTextLabel/Button/LineEdit nodes inherit automatically.
Add IMPLANT_TEXT_COLOR/DIM/PULSE constants to constants.gd.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

client/assets/fonts/OFL.txt

@@ -0,0 +1,93 @@
+Copyright 2011 The Michroma Project Authors (https://github.com/googlefonts/Michroma-font)
+
+This Font Software is licensed under the SIL Open Font License, Version 1.1.
+This license is copied below, and is also available with a FAQ at:
+https://scripts.sil.org/OFL
+
+
+-----------------------------------------------------------
+SIL OPEN FONT LICENSE Version 1.1 - 26 February 2007
+-----------------------------------------------------------
+
+PREAMBLE
+The goals of the Open Font License (OFL) are to stimulate worldwide
+development of collaborative font projects, to support the font creation
+efforts of academic and linguistic communities, and to provide a free and
+open framework in which fonts may be shared and improved in partnership
+with others.
+
+The OFL allows the licensed fonts to be used, studied, modified and
+redistributed freely as long as they are not sold by themselves. The
+fonts, including any derivative works, can be bundled, embedded, 
+redistributed and/or sold with any software provided that any reserved
+names are not used by derivative works. The fonts and derivatives,
+however, cannot be released under any other type of license. The
+requirement for fonts to remain under this license does not apply
+to any document created using the fonts or their derivatives.
+
+DEFINITIONS
+"Font Software" refers to the set of files released by the Copyright
+Holder(s) under this license and clearly marked as such. This may
+include source files, build scripts and documentation.
+
+"Reserved Font Name" refers to any names specified as such after the
+copyright statement(s).
+
+"Original Version" refers to the collection of Font Software components as
+distributed by the Copyright Holder(s).
+
+"Modified Version" refers to any derivative made by adding to, deleting,
+or substituting -- in part or in whole -- any of the components of the
+Original Version, by changing formats or by porting the Font Software to a
+new environment.
+
+"Author" refers to any designer, engineer, programmer, technical
+writer or other person who contributed to the Font Software.
+
+PERMISSION & CONDITIONS
+Permission is hereby granted, free of charge, to any person obtaining
+a copy of the Font Software, to use, study, copy, merge, embed, modify,
+redistribute, and sell modified and unmodified copies of the Font
+Software, subject to the following conditions:
+
+1) Neither the Font Software nor any of its individual components,
+in Original or Modified Versions, may be sold by itself.
+
+2) Original or Modified Versions of the Font Software may be bundled,
+redistributed and/or sold with any software, provided that each copy
+contains the above copyright notice and this license. These can be
+included either as stand-alone text files, human-readable headers or
+in the appropriate machine-readable metadata fields within text or
+binary files as long as those fields can be easily viewed by the user.
+
+3) No Modified Version of the Font Software may use the Reserved Font
+Name(s) unless explicit written permission is granted by the corresponding
+Copyright Holder. This restriction only applies to the primary font name as
+presented to the users.
+
+4) The name(s) of the Copyright Holder(s) or the Author(s) of the Font
+Software shall not be used to promote, endorse or advertise any
+Modified Version, except to acknowledge the contribution(s) of the
+Copyright Holder(s) and the Author(s) or with their explicit written
+permission.
+
+5) The Font Software, modified or unmodified, in part or in whole,
+must be distributed entirely under this license, and must not be
+distributed under any other license. The requirement for fonts to
+remain under this license does not apply to any document created
+using the Font Software.
+
+TERMINATION
+This license becomes null and void if any of the above conditions are
+not met.
+
+DISCLAIMER
+THE FONT SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTIES OF
+MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT
+OF COPYRIGHT, PATENT, TRADEMARK, OR OTHER RIGHT. IN NO EVENT SHALL THE
+COPYRIGHT HOLDER BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
+INCLUDING ANY GENERAL, SPECIAL, INDIRECT, INCIDENTAL, OR CONSEQUENTIAL
+DAMAGES, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+FROM, OUT OF THE USE OR INABILITY TO USE THE FONT SOFTWARE OR FROM
+OTHER DEALINGS IN THE FONT SOFTWARE.

client/assets/fonts/michroma_ui.tres

@@ -0,0 +1,8 @@
+[gd_resource type="FontVariation" load_steps=2 format=3]
+
+[ext_resource type="FontFile" path="res://assets/fonts/Michroma-Regular.ttf" id="1_base"]
+
+[resource]
+base_font = ExtResource("1_base")
+spacing_glyph = 1
+spacing_space = 1

client/assets/theme/game_theme.tres

@@ -0,0 +1,20 @@
+[gd_resource type="Theme" load_steps=2 format=3]
+
+[ext_resource type="FontVariation" path="res://assets/fonts/michroma_ui.tres" id="1_font"]
+
+[resource]
+default_font = ExtResource("1_font")
+default_font_size = 14
+
+Label/colors/font_color = Color(0.878, 0.969, 0.98, 1)
+Label/font_sizes/font_size = 14
+
+RichTextLabel/colors/default_color = Color(0.878, 0.969, 0.98, 1)
+RichTextLabel/font_sizes/normal_font_size = 14
+
+Button/colors/font_color = Color(0.878, 0.969, 0.98, 1)
+Button/colors/font_hover_color = Color(0.91, 0.773, 0.278, 1)
+Button/font_sizes/font_size = 14
+
+LineEdit/colors/font_color = Color(0.878, 0.969, 0.98, 1)
+LineEdit/font_sizes/font_size = 14

client/project.godot

@@ -24,6 +24,11 @@ UIStrings="*res://scripts/autoloads/ui_strings.gd"
 FogState="*res://scripts/autoloads/fog_state.gd"
 AudioManager="*res://scripts/autoloads/audio_manager.gd"
 
+[gui]
+
+theme/custom="res://assets/theme/game_theme.tres"
+theme/custom_font="res://assets/fonts/michroma_ui.tres"
+
 [display]
 
 window/size/viewport_width=1920

client/scripts/constants.gd

@@ -80,3 +80,10 @@ const PERIPHERAL_ALPHA: float = 0.5
 # Facing direction indicator
 const FACING_INDICATOR_SIZE: float = 6.0
 const FACING_INDICATOR_OFFSET: float = 14.0
+
+# #517: Implant UI font color grading — avoid pure white, project through a lens
+const IMPLANT_TEXT_COLOR: Color = Color("#E0F7FA")   # Cyan-white — primary text
+const IMPLANT_TEXT_DIM: Color = Color("#9EBFC4")     # Dimmed variant — secondary text
+const IMPLANT_PULSE_MIN: float = 0.85               # Alpha pulse floor
+const IMPLANT_PULSE_MAX: float = 1.0                # Alpha pulse ceiling
+const IMPLANT_PULSE_PERIOD: float = 2.5             # Seconds per pulse cycle

client/ui/interaction_list.gd

@@ -16,8 +16,8 @@ const FADE_IN := 0.12
 const FADE_OUT := 0.10
 const LABEL_HEIGHT := 22
 const LABEL_GAP := 2
-const INSERT_FG := Color("#c8d0e0")
-const INSERT_DIM := Color("#8b8ba0")
+const INSERT_FG := Constants.IMPLANT_TEXT_COLOR
+const INSERT_DIM := Constants.IMPLANT_TEXT_DIM
 const INSERT_BG := Color(0.05, 0.05, 0.08, 0.7)
 
 var _showing: bool = false