docs: add pitch shifting documentation

F6/F7 keybindings, audio.pitch config option, voice pitch section
in USAGE.md.  Updated profiling notes to reflect per-thread coverage.

README.md

@@ -11,6 +11,7 @@ TUI Mumble client with voice support and push-to-talk.
 - Chat input history (Up/Down arrow navigation)
 - Self-deafen toggle
 - Volume control (input/output gain)
+- Voice pitch shifting (deeper/higher)
 - Client certificate authentication
 - Auto-reconnect on network loss
 - Config hot-reload (F5)
@@ -25,6 +26,8 @@ TUI Mumble client with voice support and push-to-talk.
 | `F3` | Cycle input volume |
 | `F4` | Push-to-talk (configurable) |
 | `F5` | Reload config from disk |
+| `F6` | Pitch down (1 semitone) |
+| `F7` | Pitch up (1 semitone) |
 | `Enter` | Send message / join channel (sidebar) |
 | `Up` | Previous message (input) / previous channel (sidebar) |
 | `Down` | Next message (input) / next channel (sidebar) |
@@ -57,6 +60,7 @@ username = "myname"
 [audio]
 # output_gain = 1.0
 # input_gain = 1.0
+# pitch = 0          # semitones, -12 to +12
 
 [ptt]
 key = "f4"

docs/USAGE.md

@@ -17,6 +17,8 @@ tuimble --host mumble.example.com --user myname
 | `F3` | Cycle input volume |
 | `F4` | Push-to-talk (configurable) |
 | `F5` | Reload config from disk |
+| `F6` | Pitch down (1 semitone) |
+| `F7` | Pitch up (1 semitone) |
 | `Enter` | Send message / join channel (sidebar) |
 | `Up` | Previous message (input) / previous channel (sidebar) |
 | `Down` | Next message (input) / next channel (sidebar) |
@@ -45,8 +47,8 @@ python3 -m pstats /tmp/tuimble.prof   # interactive explorer
 # pip install snakeviz && snakeviz /tmp/tuimble.prof
 ```
 
-Note: cProfile captures the main thread only. Background workers
-started with `@work(thread=True)` are not included.
+Profiling covers both the main thread and all worker threads
+(including the audio send loop where pitch shifting runs).
 
 ## Volume Control
 
@@ -60,6 +62,21 @@ output_gain = 0.75   # 0.0 to 2.0 (default 1.0)
 input_gain = 1.5     # 0.0 to 2.0 (default 1.0)
 ```
 
+## Voice Pitch
+
+`F6` and `F7` adjust outgoing voice pitch in 1-semitone steps,
+ranging from -12 to +12. Negative values make the voice deeper,
+positive values make it higher. The current setting is shown in the
+status bar when non-zero.
+
+```toml
+[audio]
+pitch = 3            # semitones, -12 to +12 (default 0)
+```
+
+When pitch is 0, the processing step is skipped entirely (no CPU
+overhead).
+
 ## Client Certificates
 
 For servers requiring client certificate authentication:
@@ -77,7 +94,7 @@ Both must be PEM-encoded. Leave empty to connect without a certificate.
 `F5` reloads `~/.config/tuimble/config.toml` from disk.
 
 **Safe changes** (applied immediately): PTT key/mode/backend, audio
-gain values.
+gain values, pitch.
 
 **Restart-requiring changes** (server settings, audio device/rate):
 shown as warnings. Press `F5` again to confirm reconnect, or any