chore: fixing various typos

Merge https://github.com/google/adk-python/pull/4175

### Link to Issue or Description of Change

**1. Link to an existing issue (if applicable):**

N/A: just fixing typos discovered while reading the repo

**2. Or, if no issue exists, describe the change:**

No code change, just typo fixes: see commit diffs for all details

**Problem:**

Trying to improve overall repo quality

**Solution:**

Fixing typos as they get discovered

### Testing Plan

N/A

**Unit Tests:**

N/A

**Manual End-to-End (E2E) Tests:**

N/A

### Checklist

- [X] I have read the [CONTRIBUTING.md](https://github.com/google/adk-python/blob/main/CONTRIBUTING.md) document.
- [X] I have performed a self-review of my own code.
- [ ] I have commented my code, particularly in hard-to-understand areas.
- [ ] I have added tests that prove my fix is effective or that my feature works.
- [X] New and existing unit tests pass locally with my changes.
- [ ] I have manually tested my changes end-to-end.
- [ ] Any dependent changes have been merged and published in downstream modules.

COPYBARA_INTEGRATE_REVIEW=https://github.com/google/adk-python/pull/4175 from didier-durand:fix-typos-c 16e93ed2d9bc153fa0332ab1ae39633fcc5056e9
PiperOrigin-RevId: 858751240

src/google/adk/apps/app.py

@@ -43,7 +43,7 @@ class ResumabilityConfig(BaseModel):
   """The config of the resumability for an application.
 
   The "resumability" in ADK refers to the ability to:
-  1. pause an invocation upon a long running function call.
+  1. pause an invocation upon a long-running function call.
   2. resume an invocation from the last event, if it's paused or failed midway
   through.
 

src/google/adk/cli/adk_web_server.py

@@ -205,7 +205,7 @@ class RunAgentRequest(common.BaseModel):
   new_message: types.Content
   streaming: bool = False
   state_delta: Optional[dict[str, Any]] = None
-  # for resume long running functions
+  # for resume long-running functions
   invocation_id: Optional[str] = None
 
 

src/google/adk/flows/llm_flows/base_llm_flow.py

@@ -73,7 +73,7 @@ DEFAULT_ENABLE_CACHE_STATISTICS = False
 class BaseLlmFlow(ABC):
   """A basic flow that calls the LLM in a loop until a final response is generated.
 
-  This flow ends when it transfer to another agent.
+  This flow ends when it transfers to another agent.
   """
 
   def __init__(self):
@@ -393,8 +393,8 @@ class BaseLlmFlow(ABC):
         current_invocation=True, current_branch=True
     )
 
-    # Long running tool calls should have been handled before this point.
-    # If there are still long running tool calls, it means the agent is paused
+    # Long-running tool calls should have been handled before this point.
+    # If there are still long-running tool calls, it means the agent is paused
     # before, and its branch hasn't been resumed yet.
     if (
         invocation_context.is_resumable